Troubleshooting
The first thing you should do if you are experiencing problems, is to check the Files Gallery built-in diagnostics tool. This operation will specifically check for server and PHP functionality required by Files Gallery for certain features. Access your diagnostics in browser by appending parameters ?action=tests to your Files Gallery url.
https://yourwebsite.com/?action=tests
Support
For support, please post questions in forum.files.gallery:
Support forum