Yes, scheduled workflows will count as a seat on your plan. If you’re already at the max users for you plan you’ll need to increase your seat count. You can read more about active users here.
If I want to run multiple scheduled workflows, will I have to buy a user seat pr schedule? Or pr workflow? Pr Project? Or will this user be used automatically for all scheduled jobs?
It seems like a very weird requirement/way of doing things to me. Fair enough (maybe) if you want scheduled workflows to be an additional ad-hoc paid feature for 15$/month, but this implementation of it is not logical to me.