Which access control system should I start distributing?

I own a small door repair/ service company. I’m wanting to start offering card reader/ access control services due to customer requests. I have lots of experience with the hardware integration side, but not much experience with the controller/ software part, but I’m not completely green. Looking for a system that can handle 2-8 doors per controller. Need to be able to access remotely. Most use cases will be small to medium warehouses, local government offices, churches, etc.

What would be some good recommendations?