There have been similar reports and discussions in other threads here in the group.
You will have to create a service override (systemctl edit grommunio-admin-api) or directly patch the grommunio-admin-api.service config.
Needed dependencies go here in the After-directive:
[Unit]
Description=grommunio admin api
After=mariadb.service mysql.service grommunio-admin-api.socket
...
However, the devs might work on general solutions for these kind of issues, so keep an eye on the discussions.
