What opal? May i see? I wanna try.
You need to download the actual game from the Play Store first:
1) Get to stage 1-6 to unlock the shops.
2) Go to the settings menu (top right of screen) and link your FB and Google Play accounts.
3) You need to spend $1 (real money) in the shop to buy/top up Opals.
4) Go back into settings and save your game data to the cloud.
4.1) *Extra Step* I'd close out the game and then reload it. Go into settings and ensure you can load that previous save.
5) Close out/uninstall the game.
6) Come back to Platinsmods.com and download the signed APK game file.
7) Install/open game. Follow opening prompts till your in stage 1-1.
8) abort stage to return to main screen.
9) go into settings and re-link your FB account.
10) Load save from the cloud.
11) Enjoy never decreasing Opals with the mod!