Hello fabian,
Here's my /etc/fstab mount
//192.168.10.254/backup_proxmox /mnt/backup cifs credentials=/home/SOMEUSER/.smbcredentials,uid=34,noforceuid,gid=34,noforcegid,defaults,noauto,nofail,x-systemd.automount,x-systemd.requires=network-online.target 0 0
The datastore creation has been done...