Dockerfile broken or wrong usage ?

[CvH]

I tried to build a docker image from the docker file but this failed.
I am no docker expert so maybe I am doing something completely wrong.
Basically the same commands work well at rhasspy so I am not sure if something is required but not documented somewhere.

git clone https://github.com/synesthesiam/voice2json.git
cd voice2json/
./configure
make
sudo DOCKER_BUILDKIT=1 docker build .

ubuntu:~/voice2json$ sudo DOCKER_BUILDKIT=1 docker build .
[+] Building 1.1s (20/23)                                                                                                                                                                                                      
 => [internal] load build definition from Dockerfile                                                                                                                                                                      0.0s
 => => transferring dockerfile: 38B                                                                                                                                                                                       0.0s
 => [internal] load .dockerignore                                                                                                                                                                                         0.0s
 => => transferring context: 35B                                                                                                                                                                                          0.0s
 => [internal] load metadata for docker.io/library/debian:buster                                                                                                                                                          0.7s
 => [internal] load build context                                                                                                                                                                                         0.0s
 => => transferring context: 4.50kB                                                                                                                                                                                       0.0s
 => CACHED [build 1/9] FROM docker.io/library/debian:buster@sha256:94ccfd1c5115a6903cbb415f043a0b04e307be3f37b768cf6d6d3edff0021da3                                                                                       0.0s
 => CANCELED [build 2/9] RUN --mount=type=cache,id=apt-build,target=/var/apt/cache     apt-get update &&     apt-get install --no-install-recommends --yes         python3 python3-dev python3-setuptools python3-pip py  0.3s
 => CANCELED [run  2/11] RUN --mount=type=cache,id=apt-run,target=/var/apt/cache     apt-get update &&     apt-get install --yes --no-install-recommends         python3         libportaudio2 libatlas3-base libgfortra  0.3s
 => ERROR [build 3/9] COPY download/shared /build/download/                                                                                                                                                               0.0s
 => ERROR [build 4/9] COPY download/amd64/ /build/download/                                                                                                                                                               0.0s
 => CACHED [build 5/9] COPY m4/ /build/m4/                                                                                                                                                                                0.0s
 => CACHED [build 6/9] COPY configure config.sub config.guess      install-sh missing aclocal.m4      Makefile.in setup.py.in voice2json.sh.in voice2json.spec.in      requirements.txt      /build/                      0.0s
 => CACHED [build 7/9] RUN cd /build &&     ./configure --enable-in-place --prefix=/usr/lib/voice2json/.venv                                                                                                              0.0s
 => CACHED [build 8/9] COPY scripts/install/ /build/scripts/install/                                                                                                                                                      0.0s
 => CACHED [build 9/9] RUN --mount=type=cache,id=pip-build,target=/root/.cache/pip     cd /build &&     make &&     make install                                                                                          0.0s
 => CACHED [run  3/11] COPY --from=build /usr/lib/voice2json/ /usr/lib/voice2json/                                                                                                                                        0.0s
 => CACHED [run  4/11] COPY --from=build /build/voice2json.sh /usr/lib/voice2json/                                                                                                                                        0.0s
 => CACHED [run  5/11] COPY etc/profile.defaults.yml /usr/lib/voice2json/etc/                                                                                                                                             0.0s
 => CACHED [run  6/11] COPY etc/profiles/ /usr/lib/voice2json/etc/profiles/                                                                                                                                               0.0s
 => CACHED [run  7/11] COPY etc/precise/ /usr/lib/voice2json/etc/precise/                                                                                                                                                 0.0s
 => ERROR [run  8/11] COPY site/ /usr/lib/voice2json/site/                                                                                                                                                                0.0s
------
 > [build 3/9] COPY download/shared /build/download/:
------
------
 > [build 4/9] COPY download/amd64/ /build/download/:
------
------
 > [run  8/11] COPY site/ /usr/lib/voice2json/site/:
------
failed to compute cache key: "/site" not found: not found