Workdays is now an option you can choose when setting up Reports (in your Profile) or Recurring Card Enrollments (if you are a Manager). Here's what it looks like in the Recurring Card Enrollment setup:
And here it is in the Reports set up:
For the Workdays choice to mean something, your Team Admin needs to choose the days of the week your team considers to be workdays. One set of workdays will apply to everyone on the Team.
If you are a Team Admin, set up your workdays by going to Team Settings in the side menu and choosing Settings. Look for the following checkboxes about mid-way down the page: