The Unfi line is designed to work within a centralized management system. Meaning you’ll need the controller software (self hosted on a pc, cloudkey, etc) to do the initial adoption and setup, and to make any subsequent changes. People find this attractive as it makes things easier. One interface for multiple devices. However, it can also get you into a vendor lock, where if you want to add a non-unifi device, even by ubiquti you’ll have to use another wed interface. For instance their edge line uses UNMS.
These devices can run without a controller, you just wont have the stats or interface to look at when the controller is offline. You can use something like hostifi.
Personally, I ditched a unifi stack for opnsense, hpe/aruba switching, and aruba and grandstream wireless. Never looked back. Things go so smooth, I forget about my network.