Error 500 when attempting to preview xlsx spreadsheets via PDFGen in BioCollect

[PHBueno]

Description: I'm encountering an issue when deploying BioCollect in both Staging and Production environments. Recently, after installing the PDFGen submodule to generate previews for xlsx spreadsheets, I started receiving a 500 error when trying to view the preview of any spreadsheet.

Scenario:

• PDFGen successfully receives the request from BioCollect.
  However, when PDFGen attempts to download the spreadsheet to convert it, it returns a 404 error, even though the file exists in BioCollect.

• This behavior has been observed both in my local BioCollect instance and on the Australian BioCollect site (https://biocollect.ala.org.au/), where attempting to preview spreadsheets also results in a 500 error.

Possible Cause: Based on the logs, I believe the issue is related to authentication. When I try to download a file directly from BioCollect without being authenticated, I get the same 404 error. This suggests that PDFGen may be failing to authenticate correctly when attempting to download the spreadsheet.

Steps to Reproduce:

1. Deploy BioCollect with the PDFGen submodule.
2. Attempt to preview an xlsx spreadsheet.
3. Observe the 500 error, and check that PDFGen receives a 404 error when trying to download the spreadsheet.

Notes:

The file does exist in BioCollect and is accessible when downloaded directly by an authenticated user.
The issue seems to stem from the authentication between BioCollect and PDFGen during the file download.
Request: I would appreciate assistance in investigating whether there is an authentication configuration issue between BioCollect and PDFGen or another reason why PDFGen is receiving a 404 error when attempting to download the spreadsheet for conversion.