Hello @petra-pik , thanks for your response. Unfortunately, the android app still reports "wrong email/password". Copying the same credentials into the browser works. Meanwhile, I reinstalled the app, with no avail.

What I did:

1. installed android app and "registered" using the passwordless "log-in with google account" function.
2. realized that the website doesn't allow log-in with google account, so I registered with the same gmail address and a password.
3. I paid for a years worth subscription.
4. Now I can login into the website with both my username "Zsolt Sz" and my gmail address.
5. But I cannot log in into the app. It reports either wrong email (if I use the Username), or wrong password if I use the copy-pasted tripple-checked password together with my mail address.

I assume that a dev should remove my "login with google account"-account, as it collides with my same-mail-address account. Or did I miss something?