Your comment is omitting that the post covered this exact point in detail: they had just done the same operating on their personal profile where you have to typ

Your comment is omitting that the post covered this exact point in detail: they had just done the same operating on their personal profile where you have to type [username]/[username]. [organization]/[organization] is the obvious corrolary. Anyways it's embarrassing that Github made this same mistake themselves, and yet couldn't spare the time for a massive content creator contributing to their platform