Does a free members-only community app for a gym count as commercial use on Hobby?

Hi, I'm running a small community web app on the Hobby plan for members of a CrossFit gym. Members use it to see the daily workout, log personal records, and chat.

It is completely free for members.
No payments, no ads, no product sales, no affiliate links.
Nobody is paid to build or host it. I built it myself as part of a coding course project.
It does not advertise or sell the gym's memberships.

The Fair Use Guidelines say Hobby is for non-commercial personal use. Would this kind of members-only community app be allowed on Hobby, or should it be on Pro? Thanks!