The game Titanfall wants me to sign in on profil whit multiplayer privileges to play online. ??

It's saying "You must be signed in to a gamer profile with multiplayer privileges to play online." I am signed in and have a gold membership?? What's going on??

You need Gold (soon to be Game Pass Core) or Game Pass Ultimate (which includes Gold) in order to play online multiplayer. Game Pass for Console does not include online multiplayer privileges.

I do actually have Game Pass Ultimate active

Do you have Game Pass Core or Game Pass Ultimate? You would need one of those to play online. Free-to-play games like Ark and Fall Guys do not require a subscription.

Alright, let's try something else!

If the Xbox One console you guys are using is set as your son's home console, you will be able to share his Xbox Live benefits and be able to play online with your account. Let's have you try logging into the Xbox One console with your Xbox Live account
you're posting with. When you sign in, make sure you're the only profile logged in. When you're signed in, try to play TItanfall. If you're able to see the data centers and play an multiplayer game, have your son sign in with his Xbox Live account and play
while you're signed in and see if it lets him play Titanfall. The reason why I want to try that is to see if there are any profile restrictions in his account that would cause this issue.

Thank you so much for your patience, I'm sorry to hear any frustration this has caused!