Yeah, weird behaviour. I even tried installing Brave and setting it as the default browser, but didn't help.
This is probably not the official way of getting access, but this is how I got my app to work (just installed it from the Play store):
- remember I installed Brave [temporarily] and set it to default. Maybe it's unnecessary.
- tap Access Codes, Set up a new access code
- "I do not have a QR code" (you could probably create one online)
- Sign in with app
- Sign in with your Gateway user ID, enter 2FA code
- create a PIN
I logged in, uninstalled Brave, app still works.