Installing Regarder Minimal Black watch face is easy:

Just open the Mobile Companion app and follow the instructions there.
In case this does not work. You can use a PC and install it from there

If this option still does not work you can install the watch face from your wear OS Device, here are the instructions:

1. On your Wear OS smartwatch, open the Google Play Store.
2. Search for "Regarder Minimal Black" and select the app from the search results.
3. Tap "Install" to begin the installation process.
4. Once the installation is complete, you can find the watch face in the "Watch Faces" section of your smartwatch's settings.
5. Select Regarder Minimal Black as your active watch face.