I did a fresh Installation on a Samba AD member server, both are Nethserver 7.9… I was able to login with the user admin with AD password… Do you need something else?
Ideally eventually take a snapshot of a vm but before to alter the database I take a copy to /var/lib/nethserver/backup_db_dolibarr/ so we should have no problem.
Even that we could still use the manual procedure to alter mysql db at https://url/dolibarr/install/index.php but we should not need it.