If the skin comes as an APK file (or you are customizing an APK), you may need to sign it to install it on your device.
Note: As UCCW is not maintained, consider trying alternatives like "Widgets by You" if experiencing issues. If you want to know more, I can: Show you where to Guide you through manually signing the apk with a computer Explain how to fix weather display issues in UCCW Let me know which option is most helpful! apk-signer - Apps on Google Play Download uccw495 sign apk
For security, it is highly recommended to download UCCW skins from reputable sources like the Google Play Store or Uptodown to avoid malware. Steps to Download and Use a UCCW Skin If the skin comes as an APK file
Use a tool like apk-signer from the Google Play Store. apk-signer - Apps on Google Play For security,
Use apksigner from the Android SDK build-tools to sign and zipalign the file.
Long-press on your home screen, select Widgets, and choose a UCCW widget size. Select the imported skin from the list. Signing an APK
Download the main "UCCW - Ultimate custom widget" app from the Google Play Store.