In reply to Ciro:
There are two walls in Nottingham, one is a stone's throw away from St Ann's, i.e. grim central, the other is in Old Basford, i.e. grim but not central. There is the university wall, which has secure bike storage, but that is nowhere near in the same league.
What the Depot needs to do if you ask me is to fit a gate between the main entrance and the bike storage. The layout makes that quite possible. It could open with the depot membership barcodes, although I suspect RockGymPro has no APIs allowing that check which would make it rather more annoying to do.