On second look the QuickStart cable will push onto the blue isolator TV/Data port. Just unscrew the old cable from it.
cannot agree with that its got an 8Db attenuator there for a reason you would think so i wold leave that in the circuit
to the OP just screw whats there into the back of the hub - see if it fires up - if it does post the upstream and downstream levels
log into hub3 - 192.168.0.1 [or 192.168.100.1 if in modem mode] - DON'T SIGN IN, click - click router status [centre of screen] - and post the downstream and upstream figures - to see those press on the grey buttons/boxes labelled - upstream - downstream
if its an earlier hub button is top right
might be a bit more complicated than that as it will be the first log in but just follow what you see as instructions