Install Lemmy from Scratch docs seem broken

I'm trying this on Ubuntu 22.04 Rust's cargo install seems to keep creating permission problems between what I have to install, compile and what gets published in the cargo "registry", which causes issues at runtime when I run as lemmy:lemmy through systemctl.

If I run: cargo install lemmy_server --target-dir /usr/bin/ --locked --features embed-pictrs as a non-root user, I get permission denied issues with /usr/bin/.future-incompat-report.json and /usr/bin/release

If I run the build as a root user, and then manually copy the binaries to /usr/bin and chmod them to lemmy:lemmy, then try to run as lemmy:lemmy, it appears the binary is trying to access some "registry" files in /root/.cargo/registry (for which of course it does not have permissions.)

How do I fix this?