New macOS Sequoia 15.3.1 - install issues

[m3ki]

Hi all,

I followed the install procedures to the letter as far as I can tell and still experiencing issues.

Issue #\1

1. In step #\2 I chose NO not to install Determinate Nix as requested. However on the step #\9

nix run .#build

I get the following error.

error: Build user group has mismatching GID, aborting activation
The default Nix build user group ID was changed from 30000 to 350.
You are currently managing Nix build users with nix-darwin, but your
nixbld group has GID 350, whereas we expected 30000.

Possible causes include setting up a new Nix installation with an
existing nix-darwin configuration, setting up a new nix-darwin
installation with an existing Nix installation, or manually increasing
your `system.stateVersion` setting.

You can set the configured group ID to match the actual value:

    ids.gids.nixbld = 350;

We do not recommend trying to change the group ID with macOS user
management tools without a complete uninstallation and reinstallation
of Nix.

I uninstalled and reinstalled nix three times at this point and i get the same error.
I even trying to run the prepare script from the linked page before and after the initial install of NIX. Same issue.
I gotta be missing something somewhere.

Issue/question #\2

I did prepare my own private nix-secrets repo, however there is no mention as to what code/config to add to the repo and where. Is it done automatically somewhere?

Thanks so much for any help.