I updated foundry V2

I updated today mainly because of the Mason stacks.
Stacks won’t work?
The Mason Template Pack requires Foundry v2, Potion Pack and Thunder Pack to use all of the included templates. (that was in the email, no mentioning about stacks version).
I have stacks 3.5. is that the reason?
V2 is works ok.

Templates is a feature of Stacks v4. The templates and externals were added by Isaiah in his v4 update.