I also have the same problem.
When I fill in "./sites/default/files/public/mindmax/GeoLite2-City.mmdb" in GeoIP Database path, the prompt "Directory does not exists, or is not accessible." is displayed and the Settings cannot be saved,
Filling in "./sites/default/files/public/mindmax/" has no error and can be saved, but the address of the visitor report shows "none",
I made sure they had the appropriate clearance
Thank you very much.
This problem was solved after I reinstalled visitor in composer.
The problem may have been caused by manually updating the module after I moved the project to a new environment.
liriji77 → created an issue.