Do I need a Google account to activate YouTube? from charles hensen's blog

Yes, you need a Google account to activate YouTube on your device. If you don’t have one, you can create a Google account for free on the Google account creation page. 

Yt.be/activate is a web page provided by YouTube that allows you to link your YouTube account to various devices such as smart TVs, streaming media players, and gaming consoles. It’s a crucial step to enable you to watch YouTube content on these devices. You need to use yt.be/activate when you want to access your YouTube account on a device other than your computer or mobile device. This is necessary to ensure that your account is securely linked to the device.