"does printf work??" error after booting High Sierra from portable HDD with Clover

I downloaded the dmg from here, flashed it onto my portable HDD with TransMac and then attempted to boot from it, but I'm greeted with a rather cryptic error: "does printf work??"

CPU: Ryzen 5 1600

Motherboard: MSI B350 Tomahawk

GPU: MSI Gaming X GTX 1080