If you can't use the app, try accessing the site through Firefox instead. It is far more user friendly than Android's "Browser", and you can actually do more stuff through the site than the app (for being a paid app, shouldn't you be able to do MORE than the free site?).
The app is identical to the old free version, so if you can't use it, you can't use it.
Do you have an email address on file in your settings? You may be able to add one and then log in "normally"?
Do something everyday that your future self will thank you for.
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