Hm, says the App doesn't work with my device, but can maybe borrow another and try in the next day or two.
I tried through the link, I can never get the red join button to appear from the direct link, I have to go to the clubs section and click on some random clubs until the button appears for one of them, then if I go back to the GT Planet club the button will be there too.
When I can get the red join button to appear I can click on the second join button in the pop up with the assists/etc info and then the window just goes away and nothing happens, where as all of the other ones there is another pop up that says "Congratulations you are now part of _____" after clicking the join button.
I sent RYAN and Magpie requests but only RYAN accepted, but that made it appear on my list. I don't think I specifically have to have the club leader on the friends list though because it lets me join other clubs that RYAN is in, including the Modern Classics one.
Quite frustrating...