Every booking gets a time-limited PIN or QR code that is only valid during the booked time.
Your light controller asks spooorts whether a booking is active and switches the lights on just for that time.
You connect the hall lights, the heating if you like, and the door lock through your own hardware controller.
A door, turnstile or gate become access points. Every code is checked in real time and entry is granted or denied.
Every entry is logged, so even with no staff on site you can always trace who was there and when.
Players receive their access code in the app and with the booking confirmation. Arrive, unlock and go.