Web Log In with Username instead of EMail address

The Web-Interface provides the choice for using Email or Username for logging into Seafile.

In Profile Settings I gave the user a name.

Using this given name as Username and Password for this user leads to ‘Incorrect email or password’.

How to Log In using a name instead of an e-mail address?

seafile-server_6.0.9_x86-64 (CE)

https://manual.seafile.com/deploy/using_ldap.html
or
https://manual.seafile.com/deploy/shibboleth_config.html

I was afraid, that this will be that way.

Thanks for your advice.