I'm having this same problem. Using the desktop app, I've created a new master password and go to Vault Settings>Set up Sync>Nextcloud. After adding my Nextcloud server URL to the field, when I click on Connect, I get the same "Could not connect to specified Nextcloud server. Please check your URL". What am I doing wrong? Do I need to adjust a setting in my Nextcloud set up?
I understand there is a workaround using WebDAV but it seems like the Nextcloud sync should work. The advertised Nextcloud integration is one specific reason I'm trying to switch to Enpass from 1Password. If it's just lip service then I'd like to know that upfront.
macOS Monterey 12.2.1
Apple M1 Max
Enpass 6.7.4 (938) Mac App Store
Nextcloud 22.2.3 running on Linux 5.8.0-1041-azure x86_64