Okay, here's the apk I used: I uploaded it on Google Drive because I can't remember exactly where I downloaded it from.
For people who haven't got an Android phone/tablet, the emulator you need is Nox Emulator, which can be grabbed from here. You just install it and use it as you normally would an Android device.
As for how to use Lucky Patcher to bypass beta errors, etc., here's what I did to make it all work:
1. Download and install the apk of the game
2. Open Lucky Patcher, select Harry Potter, then "Menu of Patches", then "Multi-patch"
3. Tick off "Remove License Verification" and hit "Apply"
4. Tick off both "Auto Mode" and "Remove dependencies", then click "Next step"
5. Wait for the patching to be done, then you can launch the game from Lucky Patcher itself, since you're already there
6. Once that's done, the game can go in the background and Game Guardian can be started from its own app
You can see how it all should look from these screenshots I took.