This is an awful system. Apple, you should really mirror Google here. There's no need to review subscriptions in such depth. The buyer is aware of what he's getting and if anyone were fleecing players with these you'd see a flood of complaints and apps would get taken down. Google is much more lax about all this and it makes for a smoother experience for everyone.

Best is to uncompress the tgz and then just "install from disk" in Unity and choose the package.json file from the uncompressed folder to install.

Note that for Unity builds you have to add -ld64 to both Other Linker Flags under Unity-iPhone and UnityFramework.