you did not say if it is classic or ubbthreads wwwthreads.
The docs tab up top has most info
https://www.ubbcentral.com/docs.phpIf it has a mysql database
I would do it in at least two steps start with v7.2 see if all is well check you member count for moderators users .
Ver 7 is when they added global mods and sometimes everybody becomes a moderator
Then upgrade all the way.
Importers are in the member download page.
I looked at this a little closer you need to use the importer to get to v7.2 then use the upgrade tool to get to the current v7
