Every moment of Finn on camera was useless when you think about it. He wants to only do what's best for him and Rey so he plans on leaving. Rose, some ship maintenance person, forces him to stay and then together they both figure out the Rebels are being tracked and how they can stop it. They talk to Maz, because communications on the ship seems to be working fine for long range apparently, and Maz, who teased a great story about how she acquired Luke's saber, was useless once again, only telling them to go to a casino to find someone who is teased as being someone with huge importance, only to discover he's nobody, and then leave there with someone else entirely. Ultimately they don't even disable the tracker and then escape beyond impossible odds.
It's disappointing how lazy the writing was on this. If they do plan on explaining everything in the future, then they are REALLY playing the long long game, and doing it poorly.