Macbook, Can’t boot from USB because has no administrator in startup utility


When I was going to ReInstall a fresh copy of Catalina MacOS on my Macbook pro 2019, unfortunately I deleted all partitions instead of erasing them. As my internet connection is so unstable as much as I repeated installing the OS from the net, it was failing with different errors usually related to the network errors or corrupted raw data.

I created a bootable media flash drive by these steps https://support.apple.com/en-au/HT201372.

Now when I want to boot the device from the USB drive,
Choose startup disk

it says “Security settings do not allow this Mac to use an external startup disk”.
Security settings do not allow this Mac to use an external startup disk

I waned to allow my Mac booting from external media (as this link https://support.apple.com/en-au/HT208198) but It shows me the error: “Authentication Needed – You will need to authenticate as an Administrator to change the boot security settings.”

ou will need to authenticate as an Administrator to change the boot security settings.

And when I click on Enter macOS Password I see this error : “Recovery is trying to change system settings. No administrator was found.”

Recovery is trying to change system settings. No administrator was found.

I had never set a password for my mac T2 security and also I’ve removed my Macbook from my apple account too.

I’ve searched a lot and watched lots of youtube videos but didn’t succeed anything yet. How can I fix my issue to allow me boot from the flash drive?