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.
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."
And when I click on Enter macOS Password I see this error : "Recovery is trying to change system settings. No administrator was found."
I had never set a password for my mac bios 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?