flake.nix: No such file or directory

### URL
https://docs.crossplane.io/latest/guides/install-from-source/

### What's Wrong?
I get the error "flake.nix: No such file or directory" when trying to install from source. When I try to compile from source I get the following error:

>error: path '/home/badams/crossplane' is not part of a flake (neither it nor its parent directories contain a 'flake.nix' file)

> badams@U-2GFYMTKEBBKY4:~/crossplane$ cat /etc/os-release
PRETTY_NAME="Ubuntu 22.04.5 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.5 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
UBUNTU_CODENAME=jammy