Docker enables fast local environments. DDEV simplifies the use of Docker for PHP projects. With your project configuration can shared with others on the team and version-controlled for consistency and easier maintenance.
If you already have Docker, update to the latest version, otherwise, download Docker from https://docs.docker.com/docker-for-mac/install. You will need to login with your Docker ID and password.
Install Docker to your Applications folder as with any other app (perhaps add it to your macOS Dock as well).