"Missing operating system" when trying to install from USB

Hey all, this is my first go at a hackintosh in ages. I've tried to read up as much as possible, but am running in to an issue with the USB installer where it says "Missing operating system".

What did I do:

• Read the vanilla guide from the sidebar
• The guide on osxlatitudes
• Used both a 32GB and a 8GB USB
  • Thought it might have to do with 32GB being to big or something.

• Created the USBs using the High Sierra installer

  sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/myusb 
  

• Used Clover v2.4k_r4920 , trying both

  • Clover for UEFI booting only
  • Legacy boot

• Used Clover config from here

I switched from UEFI booting to the legacy boot because I saw that both USBs weren't recognized as UEFI.

The one issue I can think of is my MacBook is on 10.12.6, I daren't upgrade as I have the dreaded late 2011 model with the dead GPU... Would be surprised if having that version would matter, but you never know.

Anybody got any ideas on what I might have done wrong/am missing?
Thanks!

System specs:

• Latitude 5590-MJR1P
• BIOS v1.6.2
  • TPM off
  • SATA operation: AHCI
  • Enabled legacy options ROMs
  • Enabled attempt legacy boot
• i5-8350u
  
• 8GB RAM
• 500GB 970 EVO Plus