Do I need Git revision control in order to use AllSpice?

In a nutshell, yes.

If you use SVN and are interested in migrating to git, the process is fairly well documented. For example, Git explains it here: https://git-scm.com/book/en/v2/Git-and-Other-Systems-Migrating-to-Git

If you are a new user, our team will be happy to help you with the process. We also have documentation on how to use Git if you want to follow along and try it out yourself.