They recommend offsetting it from the wall so the faucet will fit behind it. Apparently whoever wrote the instructions did not look at the sink to see that it had a faucet mount hole on the rim The hole on the back surface is the overflow opening. If you look at the side view it shows a sink without the back ledge and the faucet mounted on the countertop behind the sink. You glue the sink down. That fitting should NOT connect to your valve without leaking, the two threads are incompatible.