I think the Mac is definitely the issue because of how Windows handles Temp folders. But I'll tell you anyway.
1. RUn the program
2. Get Wii U common key and enter (google it, we cannot provide this to you)
3. Get Rhythm Heaven Fever title key (google it, we cannot provide this to you)
Then if you're injecting a Wii game choose Wii retail injection button on top, on the first tab choose game and choose your is or wbfs file, under 3rd tab gamepad/meta options enter the name of the game and enter any different control options but only if the game can work without a wiimote many games cannot, then click build title. You will have a WUP Installable folder transfer that folder to /install on your sd card, and install with Wup Installer GX2. That's it. If it works for you great, if it doesn't it because you're using a Mac.
Ok thanks & it’s GC Games I’m wanting to inject first & then the Wii ones afterwards & so just to double check there is
Nothing to setup elsewhere beforehand no? I can just click on the iso file for the gc game yeah? I already have that common key & title key for RHF & I’m making sure there are no other keys I have to enter anywhere? I don’t have the games on my vwii @ present only on backup on a separate hdd to the Wii u one hence why I’m asking if these need to be anywhere else beforehand thanks