You shouldn't be marketing this towards consumers. If you and your friend had this problem with the apartment gate then I'm sure more people at your apartment have to deal with it also. Why don't you talk to your apartment complex and see if they'd be interested to use it as a service for their tenants?
You should be marketing this towards apartment complex properties, not consumers living in apartment complexes.
It's usually easier to sell to someone who's experiencing a pain than it is to an upstream provider. In other words, if it was a big enough issue that you built something to fix it, and your apartment complex hasn't fixed it themselves, you probably aren't going to suddenly convince them to buy in (since they don't see the pain, or don't care).
It's more work, but you can convince the upstream provider that their customer's pain is actually causing them pain.
I would try to find a larger complex to use as a case study. Set everything up for free for them, and check their retention rate before and after the install. 1 month less of an empty apartment probably pays for your product, and if you're anything over that it's a no-brainer from the complex owner's perspective.
Management/owners have no motivation on their own to install this. They have already satisfied their insurance company by having a locked gate, any kind of locked gate. It's a plus that they can put in their consumer ads. And that's it. They have no pain.
Individuals have the pain.
Total guess, if you can get enough individuals to like it for free or cheap, then the hue and cry may motivate a manager somewhere to subscribe for $WORTHWHILE.
I thought about that as a next step, but I really don't know where to start. Talk to the manager of my leasing office? Try to find an in to the company who owns this property (and probably several others)?
You should be marketing this towards apartment complex properties, not consumers living in apartment complexes.