Trying to block users from using Outlook mobile app

For future reference, I figured out my issues with this. First, I changed the first part of the IF statement to [class match [HTTP::header "User-Agent"] contains OutlokApp] and created a group with the possible iterations of the Outlook App header. I then also realized that I did not add the rule to a virtual server, so it was never running. Once I did both, the rule worked.