most likely answer is in the point 8 how to avoid point 9:
If you selected "External" at Step 5 continue to Step 9. If you chose "Internal" you don't need to publish and can skip straight to Step 10 but your destination drive must be part of the same Google Workspace.
Also is covered in docs:
Keeping the application in "Testing" will work as well, but the limitation is that any grants will expire after a week, which can be annoying to refresh constantly. If, for whatever reason, a short grant time is not a problem, then keeping the application in testing mode would also be sufficient.