The entrance to the Hyatt is on the main arrivals level of the central hub; baggage claim is one floor below directly underneath. There are signs throughout the terminal directing travellers to the Hyatt and it's a natural and conspicuous landmark within the central hub. OP's family member does not need to spend all three hours in the lobby (there's a food court and other shops in the central hub) but I'm suggesting it would be a good place to set as the final rendezvous. The lobby itself is pretty vast.

https://orlandoairports.net/getting-around-mco/#hotel