Going back to the KISS principle, why not just set the port on the switch, in the rack that connects to the Unifi device in each apartment, to 100Mbps? If the customer wants more, say a 1Gbps connection? Increase the bandwidth at the switch, no traffic shaping necessary, it’s a hard limit of 100 Mbps.
Then you could traffic shape to other speeds if you think 1Gbps is too much.