The KB has some steps for the upgrade; it looks relatively painless
https://kb.sambapos.com/en/2-2-7-database-upgrading-from-sambapos-v3-and-or-v4-to-v5/
Once you restore the backup from within SSMS, be sure to change the compatibility level to your current SQL version (there have been a lot of updates from 2012->2017)
These posts may also be useful: