I see that someone had this issue before, but I figured I'd make a new one.

I'm running Forge 28.1.8 and I am getting an error saying that the backpacks mod needs "28.1.20" or higher. I think something went wrong on your end because that's borked.

You need a recent forge version. The list states that your forge version is 28.1.8, but uteamcore requires at least 28.1.11 and usefulbackpacks at least 28.1.20.
You need a newer forge version than 28.1.20.

The latest forge version currently is 28.1.26

...
Twitch client needs to change their things. This is REALLY confusing.

I know, the order is very very dumb. This is why it often happens.
Hopefully it works for you now!

I just tried it and it did indeed work. I apologize for making this. lol

👍
I'll close this now. Feel free to reopen if any other issues occur.