File Server restore or mount data drive

I’m using NethServer 7 in a test environment. I have the system installed and configured with Active Directory. The system is on an SSD and there is an HDD that stores user data.
I performed a new system installation with the same configuration. How can I mount the HDD with the files in this new installation without losing any data?

Note, I’m a beginner

In the storage page in Cockpit you can easily mount, see also Base system — NethServer 7 Final

Another way is to edit /etc/fstab, see also fstab - ArchWiki

BTW, Nethserver 7 is EOL so I recommend to use NethServer 8.