Yocto trouble chromium and rust.py

Hi all!
Help solve the problem with the assembly of yocto for CM3.
I am using this instruction (https://github.com/radxa/yocto-manifests) and ubuntu 20.04.

But I get error see screenshot.
Separately, I want to know what “//” means in this message (ERROR at //build/config/rust.gni:143:22:) where can I find this file?

Has anyone managed to build a Yocto for cm3?
I need linux with kernel 5.10 - 5.15. Ubuntu latest version doesn’t work.(They say they don’t support it). Yocto linux crashes when building. Can anyone help?