Adding affiliate parameters from the Microsoft store is a different process than the other affiliate programs Geniuslink supports.
Here's a video demonstrating how to do it:
For the UK Microsoft Store Affiliate Program, use this URL:
http://clkuk.tradedoubler.com/click?p=PROGRAM_ID&a=SITE_ID&g=
Click here for the full guide on adding Microsoft Store affiliate parameters into Geniuslink.