Os settings
You need to verify that Android have properly registered the callback url with Symfonium application.
Go to Android settings, then Symfonium settings.
Then click on Open by default
Verify that everything is as shown below:
Browser settings
Some browsers by default does not respect Android standards and do not open registered links with applications.
You need to change your browser configuration so that authentification is correctly send back to Symfonium.
Firefox: Set Firefox for Android to open links in native apps | Firefox for Android Help
Note: If you encounter the issue with other browsers, please contact me with a link to the corresponding browser doc so I can add it here.