This is how I got mine to work. I used the browser called 'Safari' and when the box came up for me to cancel/confirm it, I left it alone on the screen. Then I proceeded to click back in the box where they wanted me to type in my Clan name, which I retyped. It was able to retype it and then I clicked confirm to create my clan.
I just tried it and when I clicked "Continue" on the XP Boost screen I just left the page alone and let it do its thing behind the curtain. After about 5 mins I refreshed the page and to my surprise there was a tab at the top of the page with my clan name on it. I did a search to confirm and it worked.
The only thing I can't do now is access my clan page because the servers keep timing out.