Your watch is running the old Wear OS 1.x
The watch embedded part of the watch face is pushed by the Wear OS system to the watch. But for some reason it did not.
Here are a few steps you can try to enforce the installation process:
1) You can try to reboot both devices to clear the bluetooth wear os stack. Then try to open the Wear OS app settings and use Re-sync apps option.Then wait a few minutes
2) If not working : uninstall the watch face from your mobile, wait a few minutes, restart both watch & mobile, then finally install the watchface.
3) Lastly, if none of the previous solution worked, please disconnect devices(watch and phone), uninstall the watch face, restart watch and connect device again. then finally install the watchface.
Also, verify that the version of the Google Play Services installed on your watch device is uptodate. Because if your watch is running an old version of the Google Play Services (if somehow it did not update), the Wear OS will wait for the watch to have a version corresponding to the application to install (in our case 15+)