Note: you'll find two ZIP files when downloading. One for XF 2.1 and one for XF 2.2. Please, make sure to use the right version.
XenForo 2.2 is currently still in beta stage and it is not recommended to use it in production, but if you'd like to install the add-on on your test forum to check it out, now you can. This add-on may get another compatibility update before the XenForo 2.2 "gold" release.