How do I install overlays?

I would like to install nix-auto-gpt, but
I have to install the nixpkgs-friendly-overlay.
How do I do that?

see the flake for an example nix-auto-gpt/flake.nix at a4e9824cffb1fb30b24c366f433474846f9556f7 · superherointj/nix-auto-gpt · GitHub

What am I doing wrong? PS. I am a NixOs newbie, so I might be doing something stupid.

 nix --extra-experimental-features nix-command --extra-experimental-features flakes develop github:superherointj/nix-auto-gpt
[0.0 MiB DL] evaluating derivation 'github:superherointj/nix-auto-gpt#devShells.x86_64-linux.default[0.0 MiB DL] evaluating derivation 'github:superherointj/nix-auto-gpt#devShells.x86_64-linux.defauerror: builder for '/nix/store/vrrvlxj9v3ar6x29xn1sj51y21kvvd1d-python3.10-wandb-0.15.0.drv' failed with exit code 1;
       last 10 log lines:
       > tests/pytest_tests/unit_tests_old/tests_launch/
       > tests/pytest_tests/unit_tests_old/tests_launch/
       >   /build/source/tests/pytest_tests/unit_tests_old/tests_launch/ PytestUnknownMarkWarning: Unknown pytest.mark.timeout - is this a typo?  You can register custom marks to avoid this warning - for details, see
       >     @pytest.mark.timeout(320)
       > -- Docs:
       > =========================== short test summary info ============================
       > FAILED tests/pytest_tests/unit_tests/ - assert 18.910328149795532 < 15
       > = 1 failed, 680 passed, 13 skipped, 5 xfailed, 5 xpassed, 73 warnings in 125.32s (0:02:05) =
       > /nix/store/pgf87rgkzdbqhhsddpligy8xiwar63w8-stdenv-linux/setup: line 1594: pop_var_context: head of shell_variables not a function context
       For full logs, run 'nix log /nix/store/vrrvlxj9v3ar6x29xn1sj51y21kvvd1d-python3.10-wandb-0.15.0.drv'.
error: 1 dependencies of derivation '/nix/store/ccb33rkcbkgr8358cqb1bpxa45vnj7ly-python3-3.10.11-env.drv' failed to build
error: 1 dependencies of derivation '/nix/store/a614zj95rl6i21vfcfrd3hvdnbp9f562-nix-shell-env.drv' failed to build

I tried a 2. time, and it seemed to install, now I need to find the .env.template dir.