Your Watch should be connected to your mobile device.
◉ On Play Store choose your watch at the drop down list and tap install. Wait until the watch face is installed on your watch.
◉ On your mobile (Galaxy Watch 4/5/6/7) open Galaxy wearable>Watch faces >go down to downloaded and enable the new watch face.
Still problems with the installation?
The rocky road to success:
◉ from your watch go to playstore and search for the name of the watch face (cue…, cc… or crc…)
◉ install it.
◉ on your mobile (if Galaxy Watch 4/5/6/7) open Galaxy wearable>Watch faces >go down to downloaded.It should be there.
Enjoy you new watch face
You can find other ways and detailed instructions at this link: https://developer.samsung.com/sdp/blog/en-us/2022/11/15/install-watch-faces-for-galaxy-watch5-and-one-ui-watch-45#link-A