Need help to setup Dropboxsync

Operating system

iOS

Joplin version

13.5.3

Sync target

Dropbox

Editor

Markdown Editor

What issue do you have?

I am new to Joplin and want to setup the sync with dropbox. When I go to "Configuration / Synchronisation / Sync-Assistent opening..." I choose "Other" and the Popup Windows closes and does nothing. I this a bug or what should I do? (Iphone 12)

I'm not on Apple but when I go into synchronization I can choose Dropbox directly I don't go to other.