Looked at the log, again the normal startup and after that I see the retrieval of the screenshot.
It looks like somehow your Doorbell isn’t subscribed too, but in the current version that’s something that isn’t logged so hard to test.
Are you able to install the app using the CLI as described here: [HOW TO] CLI install method?
If not I will try to get some more logging in the app to check the relevant settings.
Btw, could you check the settings for your Doorbell in the Ring app, ‘RING-MELDINGEN’ should be enabled (try toggling if off-on and test the ringing again)