Ultimately I had to go to another mac and use the link provided by @Kappy (thank you).
What you do is let it download but don't run it. Then use the terminal command provided by apple
How to create a bootable installer for macOS - Apple Support
When in terminal use the command "diskutil list" to list all the disk mounted. This will tell you the name of the USB you're using to create the bootable USB. Then replace "Myvolume" with the name of your USB in terminal.
I tried using DiskmakerX but because my 16GB USB registered as 15.5GB diskmaker wouldn't use it. Doing it manually doesn't have that limitation.
Cheers to all of you who helped.