Format PiDrive using a Mac

I have just got a 250gb PiDrive and cables. I want to use it simply as storage for music files for access on a Pi3+ that runs OSMC.

Presumably, I wouldn’t need to use Berryboot as I plan on running OSMC from the sd card.

So, could I simply format the PiDrive as exfat using my Mac?

If so, do I still need to use the “multi-cable usb/PiDrive” cable connected to the mains adapter? Or can I simply hook it into the USB on my Mac and power the PiDrive from my Mac for the purpose of formatting? I would hate to learn later that power from the mains adapter somehow went through the USB into my Mac and killed it.