Owncloud new user created, login fails

Hello all;
I have successfully installed owncloud on my Raspi, login as admin works. Now I want to create a new user. Also this actually works, but when I then want to log in as the newly created user with his password, it regularly fails. I have several times checked the login data, that is, the username and the password I assigned, but still I can not log in to Owncloud as the new user I created. The user data is rejected.

Can you please help me track down my error?

Thank you very much for your support and kind regards.

Translated with DeepL

just did a test without issues. You could have a look to owncloud log file

cat /mnt/dietpi_userdata/owncloud_data/owncloud.log

The issue seems to be outside DietPi, probably you might contact ownlcoud support.