[Ring] access Ring account without PIN

[Pierre Louis]

Dear Ring community

I had to reinstall the Ring app on my Android phone (via f-droid). I was 
not able to generate a PIN to add a new device (and this is technically 
not a new device). Unfortunately, I cannot link my existing account to 
the application anymore, without having the PIN. I did not install ring 
on any other device, so I cannot generate the PIN number from anywhere else.

Is there a way to solve this problem other than create another account?
Technically, why is the PIN code needed rather than a simple 
login/password authentication method?

Thank you very much for your help
Pierre Louis