@TaymgWelcome to the forum. You mention you are signed into your account so presumably this means youare signed into MySky as https://www.sky.com/mysky If not you will get the Oops error message. You must be signed in before entering your activation code.
During setup you must also be using the same email that is registered to your account.
Once logged in go to https://www.sky.com/productsettings/streaming-tv/activate This is where you can enter your activation code that appeared on your screen during setup.
The following link is to a setup help guide:
https://www.sky.com/help/articles/setting-up-sky-glass-help
If all else fails call Sky for some additional troubleshooting.
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