@povoq I tried the general address, but it doesn’t work either. I’ll do without it. Thank you.

Hello, I just bought my first smartphone (Volla Phone with Ubuntu Touch). It looks like you need to link it to an account, because “Grouping your account details here allows apps to use them without you having to log in for each one.”
Okay. One of the solutions is Nextcloud, and I have a Nextcloud account at Zaclys. But how to do that? I create a folder in Nextcloud. I share it, get a share link. On my smartphone in Settings > Accounts, I copy this address in the URL section, in front of Username my Nextcloud username, Password my Nextcloud password, and I get as answer «Invalid host URL».
So it wasn’t like that. Could someone help me?