There is no limit on the number of users that can be added. You can additionally classify them as admin or read-only users.
Unfortunately, there is no free plan, but you can try out the entire suite of products free for 14 days.
Yes, you are free to utilize all features of GrowthScore during the free trial.
Pricing is only based on features and there is no limit on the number of reviews, referrals or testimonials obtained.