Can't activate Forza Horizon 2 key

Okay, quick update! I tried redeeming the code with a different account which doesn't have Live Gold and it works. I didn't click Redeem but it does work. This leads me to believe that I can't redeem a game I already have through Games With Gold.

Do It with a browser

I already mentioned in my original post that I have tried every possible browser and app to try and redeem it but it just doesn't work on the account which has an active Gold subscription.

So redeem It with another account

I'd like to keep my progress on my current one. And besides that, I have an account in the Forza Hub with my main account. I don't want to lose all that.

you will not lose anything, you will only redeem the game in another account, you will continue to play normally in your account, you only have to log in every time you want to play this game or else you have to set the other profile as home console in the
console

So even though I own the game on another account, I can still use my main one to keep my progress? As long as I have an account which owns the game on the current console?

Okay, quick update! I tried redeeming the code with a different account which doesn't have Live Gold and it works. I didn't click Redeem but it does work. This leads me to believe that I can't redeem a game I already have through Games With Gold.

Do It with a browser

I already mentioned in my original post that I have tried every possible browser and app to try and redeem it but it just doesn't work on the account which has an active Gold subscription.

I do not know but it may be that in your account you can no longer redeem this code, since you "bought" the game with Live Gold, then you will probably have to keep your signature active to play or You will have to redeem It in another account to play It,
set the other account as your home console or sig in every time You want to play It in your account

Okay, quick update! I tried redeeming the code with a different account which doesn't have Live Gold and it works. I didn't click Redeem but it does work. This leads me to believe that I can't redeem a game I already have through Games With Gold.

Do It with a browser

I already mentioned in my original post that I have tried every possible browser and app to try and redeem it but it just doesn't work on the account which has an active Gold subscription.

So redeem It with another account

I'd like to keep my progress on my current one. And besides that, I have an account in the Forza Hub with my main account. I don't want to lose all that.

you will not lose anything, you will only redeem the game in another account, you will continue to play normally in your account, you only have to log in every time you want to play this game or else you have to set the other profile as home console in the
console

To verify that the code works you should test using another account, without having to confirm the redemption of the code