The link goes to a guide to use Twitch's Enhanced Broadcast feature with OBS Studio - even if Twitch thinks your GPU is incompatible.
In 2024, Twitch announced that it will be possible to encode and transmit multiple resolutions in the same stream.
Native support was introduced in OBS Studio 30.2 the following year.
OBS Studio requests HTTP data from Twitch, including a (likely) temporary API key specifically to be able to stream with multiple resolutions.
In communicating with Twitch, OBS Studio supplies system information, including on the type of GPU being used. With this info, Twitch can choose whether you can stream or not. Graphics cards from NVIDIA get preferential treatment.
Let's fix that.