Then ask your LDAP admin to create the two groups for you an assign all EGroupware administrators to the “Admins” group and all EGroupware users to the “Default” group.
Or give for example the LDAP root account and password to EGroupware, so you can use EGroupware to create and manage users and groups via EGroupware. If you already done that and get the error, you should look in the webserver error-log (/etc/egroupare-docker/egroupware-logs.sh in a default installation). You probably have some Konfiguration errors with the DNs you specified.
Wie also offer professional support: https://www.egroupware.org/en/professional-support