I am posting this to help others who may encounter the same problem.
I had a problem upgrading Interviewer on my Lenovo tablet (Android 13) to the current Survey Solutions version (25.04.4).
Trying to open the downloaded apk in Chrome gave a message:
The package is invalid.
Opening the package in the File Manager (Files) app, gave:
You cannot install this app.
I spent quite some time downloading again, with and without map support, verifying the Android settings for installing unknown apps, etc.
To cut a long story short: After uninstalling the old Interviewer app, then installing the new downloaded apk finally worked.