High five for wanting to be a part of the challenge! There are a couple of steps to get signed up to the Globe Trot challenge, and after that, all of the steps are up to you.
Once you've made sure that your device is running the latest version of the app, head to your Profile (last icon along the bottom of the screen). From there, select ‘Add organisational/promo code’, and enter your unique challenge code.
If you signed up with your work email address, you’ll automatically be registered for the challenge.