Trying Vanilla install but stuck trying to build a USB installer.

Hi, So I'm trying to update my computer from an old multibeast install of El Capitan to a new vanilla install of Mojave.

This all started because I can't get any of my adobe software to install on to my mac anymore so I figure it's a good time to finally get around to learning how to do a vanilla install.

I'm folowing the very handy vanilla install tutuorial but I'm getting stuck at the part where it wants me to build the USB installer. Whenever I try to install the install macOS Mojave.app on to the USB from terminal I get the following error:

sudo: unable to stat /etc/sudoers: Permission denied

sudo: no valid sudoers sources found, quitting

It obviously seems like this is some kind of permissions issue and I think it's a similar reason to why I can't install my Adobe software anymore but I'm at a loss for what to do.

Is my only option to try to find another mac to build the USB installer on?

Computer specs:

GA-Z77X-UP5 TH

i7 3770K

GTX 670