Can't install fresh Mojave??

[Macs4u]

Just had the Mac Mini 2018 delivered and booted all up to check it all works fine. Created a bootable USB with Mohave on and booted to recovery, formatted the Mac HD and then tried to boot to the usb to I stall a fresh copy of Mohave and it won't. Shows the usb and when I click install Mohave it just flicks straight to Internet recovery. Hey ho I thought so let it do it's work and it said it can't install to the hd without an update .Said the screen will go black for up to a minute. I waited 20 mins and nothing .Booted it back up and straight back into the above .

Why can't I do what I have always done with Mac's, a fresh copy of the os?

 

[RyanXM]

You need to use Internet Recovery or create a new user and set the Startup Security to allow booting to external media.

https://support.apple.com/en-us/HT208198
https://support.apple.com/en-us/HT208330
https://appleinsider.com/articles/19/01/15/how-to-make-new-t2-secured-macs-boot-from-external-drives