Gold pass access problems

I'm just taking a wild guess here, so apologies if I'm wrong, I think the problem is that you need XBox Gold to play multiplayer games (some single player games that have a MP aspect require it too), if you get Game Pass Ultimate you get the added bonus of getting Gold at the same time as access to the Game Pass catalogue (regular Game Pass doesn't give Gold access)

You're paying for 2 different subscriptions. So you are being charged correctly.

Gold gives you the ability to play online multiplayer and access gold discounts and games with gold games. It does not include Game Pass.

Game Pass gives you access to play any of the games available on Game Pass. It does not include gold.

Gold allows you to play online multiplayer, get weekly discounts on games, and access Games with Gold.

Game Pass Ultimate includes Gold but also includes Game Pass for console and PC Game Pass. Game Pass is like Netflix, but for games. You get access to a library of games you can play while you have the subscription.

Xbox Live Gold is only for online play and gives you access to a few free games (that you keep and are able to play as long as you have Gold). You want Xbox Game Pass which gives access to a large library of game. You can also combine the Gold, Game Pass
and PC Game Pass together in Game Pass Ultimate.

There's no such thing as a Gold Unlimited. Did you buy Xbox Gold or Game Pass Ultimate?

Gold only allows to you play online multiplayer. Game Pass is like Netflix for games and allows you access to a library of games to play. Game Pass Ultimate includes both, If you only bought Gold, you would either need to buy Game Pass as well to access the game or buy the game.