After you are accepted to be a beta tester, we will use the active email address you provided, you should be able to see the install button next to the Mudra Band app on the TestFlight app.
In case you don't see it, you may need to update or add to your Apple ID. To use another Apple ID, go to Settings > Apple ID > Media and Purchases.
In case this does not work, please contact us at firstname.lastname@example.org.
This is how the Mudra Band install button should appear on your TestFlight app: