It sounds like the "Basic" plan should fit for you. There are no special pricing for any groups, prices are consistent for all.
The Basic plan allows you to have up to 5 forms at a time and collect up to 500 responses at a time in each form.
The "Plus" plan is actually cheaper and offers more but requires an annual commitment, this is a plan comparison with the US pricing: https://www.acrobat.com/formscentral/en/features/compare-plans.html
Thank you, Josh. So, the advantage to staying with the basic plan is that we can cancel at any time without losing any money . . . just paying one month at a time?
Yes, the advantage of the Basic membership is the month to month billing.