You haven’t specified the parents for the embed (if you look at the errorCode param of that error url you linked, it gives the NoParent error). The docs https://dev.twitch.tv/docs/embed/video-and-clips show that the parent param is required.
This means that if your embed is hosted on https://www.example.com/twitch that you would need to set the parent to be parent=www.example.com, if you also wanted it to work without the www. then you’d also need to add parent=example.com as well, same with any other parent (some website builders such as Wix will automatically embed iframes within another iframe of their own, which is a parent you would need to add).