You can upgrade any version from Group-Office. For some versions it’s necessary to do it in steps:
- 2.18 can upgrade to 3.7.55
- 3.7.55 can upgrade to 6.2
- 6.2 can upgrade to 6.3
Needless to say, but always make a backup before upgrading.
After the upgrade you should consider replacing the “gota” module with the new “assistant” module for better file editing on the desktop.