Hi @Ce19 and welcome to the forum. Hopefully the following will help you.
You need to be signed into your My Sky account at https://www.sky.com/mysky before entering your activation code.
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.
During setup you must also be using the same email that is registered to your account
The following link is to a setup help guide:
https://www.sky.com/help/articles/setting-up-sky-glass-help
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