Operating system
Windows
Joplin version
3.3.13
Desktop version info
Joplin 3.3.13 (prod, win32)
Sync target
Nextcloud
What issue do you have?
Under Welcome > Synchronising your notes > Setting up Nextcloud synchronisation it says "...go to your Nextcloud page, click on Settings in the bottom left corner of the page and copy the URL". This appears to be wrong, there's no such page or link (at least not in Nextcloud 10, 31.0.7). I eventually found it in the dashboard under Files > Files settings > WebDAV.
Also, this does NOT appear to be the recommended way to sync to Nextcloud. Nextcloud advises using their own sync system rather than third party WebDAV clients because it's more robust and logs accesses etc. Joplin seems to synchronise quite happily that way simply by using a local copy of the notebook in the Nextcloud folder, which is simpler to set up (no new authentication needed). The synchronise button in the bottom left still works as expected, even (especially) if offline. Can you confirm this?