After your purchase, we sent you an e-mail containing more information about what you purchased.
If you purchased a bundle, the e-mail will show all clockfaces/apps in the bundle with a download button next to each one of them.
Use that download button to go to the appstore and install the clockface/app on your watch.
If you cannot find the e-mail any more, you can perform a lookup of all your purchases at https://k-pay.io/lookup
These download links only work if you use them on the phone or tablet on which you have installed the Fitbit or Pebble app!
If the download button does not take you to the appstore, this probably means the developer has not correctly configured the appstore link in his/her account. You can contact the developer and ask him/her to fix this, or you can use the search functionality in the appstore to find the app/clockface instead.