Initially, the UDM is installed in this way and you have a network running. To make good use of the entire system, you have to go through a lot of software steps, gather knowledge and change settings, keep this in mind. I myself live in a 1930s house, but in addition to the AP of the UDM I have installed two separate APs to make a better coverage of my Wifi signal. I recommend this system if you want to find out how this system works best, it is not a plug and play set up.
Furthermore, the possibilities are 'infinite', as long as you immerse yourself in Ubiquiti's software.