Some password managers, ahem, looking at you Lockwise, ahem, don't support TOTP.
Or maybe you don't want to pay $10 per year for Bitwarden. Yes, you have my permission to be that frugal. 💸
This usually requires falling back to an authenticator app like Authy or Google Authenticator. Unless you like to swim against the current 🌊🏊 and you want to "hack" your password manager to store TOTP secrets in it somehow.
The cool app that you're looking at right now is making it easy for you to "hack" your password manager in this way.
Directly from the app, you can scan a QR code by using the device camera, or upload/drop a screenshot of a QR code if that's more convenient for you. If you already have a plaintext TOTP secret, you can just paste it in the password field and submit the form.
This will trigger what will look to your password manager like a login form submission, where only a password was submitted, so it will usually prompt you to save the password for that website, including the option to add an username.
I suggest putting a meaningful value as the username, to remember what service this TOTP secret is for.
At that point, the app will generate a one-time password matching the secret that was just added, and copy it to clipboard.
Now, because your password manager stored your TOTP secret like it's a normal password for this website, anytime you come back to it (usually when you need a one-time password) and focus the password field, it'll happily autocomplete amongst all the saved TOTP secrets that you have added in the past. Then you can click the big blue button and get your one-time password copied to clipboard. 😋