Five minutes from the ZIP to a working add-on, whichever method you prefer.
Open your account, go to the product page and hit Download. You get one archive containing the add-on and its README.
Two methods. The first is easier and works on most hosts.
XenForo unpacks the files, runs the installation steps and enables the add-on. Nothing else to do.
upload/ over your forum root, keeping the folder structureEvery add-on adds its own section under Admin CP, Options, and most add a tab of their own. The start here thread in the add-on's forum lists what is worth looking at first, in order.
Permissions matter more than options. If a feature seems missing for your members, check Admin CP, Groups and permissions before assuming it is broken.
Premium XenForo add-ons, built, sold and supported by the developer himself. One-time payments, 12 months of updates, forums that answer back.