fails to build on darwin

[permezel]

Trying to follow the Readme.md:

%  git clone https://github.com/nix-community/todomvc-nix           
Cloning into 'todomvc-nix'...
remote: Enumerating objects: 1165, done.
remote: Counting objects: 100% (763/763), done.
remote: Compressing objects: 100% (426/426), done.
remote: Total 1165 (delta 341), reused 649 (delta 250), pack-reused 402
Receiving objects: 100% (1165/1165), 9.83 MiB | 2.42 MiB/s, done.
Resolving deltas: 100% (516/516), done.
sloth% cd todomvc-nix 
sloth% nix develop
error: flake 'git+file:///Users/dap/proj/todomvc-nix' does not provide attribute 'devShells.x86_64-darwin.default', 'devShell.x86_64-darwin', 'packages.x86_64-darwin.default' or 'defaultPackage.x86_64-darwin'
       Did you mean devShell

System info:

System Version: macOS 12.3 (21E230)
Kernel Version: Darwin 21.4.0
Boot Volume: Macintosh HD
Boot Mode: Normal
...
Secure Virtual Memory: Enabled
System Integrity Protection: Enabled
Time since boot: 9 days 7:22

% nix --version
nix (Nix) 2.7.0