I see there is an option for Individual bandwidth limit, so my understanding is everybody would have the limit set for upload and download - I do have fiber 100Mb/100Mb so for 60 clients connected to that fiber what would be the best limit? Mixed clients phones and PCs.
Unless you are doing 4K streaming, the majority of video streaming (large data transfer) can function without buffering at about 8 Mbps. Some video sites use multiple data connections running concurrently, so you could do 15-16 Mbps and cover that base. Large file downloads (non-video) will “work” at any rate, so the 15-16 Mbps would work fine for them too.
That limit is per second. At any given point, the client can only consume 8 Mbps.
Sometimes thinking of data flows as a liquid helps. You can limit the amount of liquid to a “bucket a day”, but you can also limit the liquid to “a quarter turn of the faucet”. The bandwidth limit is more of the faucet type of limit as opposed to a total amount dispensed.