Install selected version.
Go to C:\Program Files (x86)\AOMEI Backupper\6.7.0, edit Version.ini and set versionCode=3 or 4 or 5 or 6

3 -> Professional
4 -> Server
5 -> Technician
6 -> Technician Plus

Put "OfflineRegistrator.exe" in Backupper installation folder and run with administrator rights.
Register with serial:

Professional
License Code: AMPR-443TV-87Z90-5LWFT

Server
License Code: AMSE-RVY06-BS788-O550S

Technician (Plus)
License Code: AMEN-L49P9-76B27-U9J38

Close "Registrator" and run Backupper