~/dozer-sandbox-workspaces (was ~/Developer/dozer-sandbox-projects):a folder named for what it holds, in your home folder. If you set defaults.projects_dir yourself, it is unchanged; existing sandboxes keep their folders. Move it with Settings › Choose… or doz config set defaults.projects_dir PATH.
brew trust --tap dozer-sandbox/tap (recent Homebrew needs it onceper Mac) and the dashboard's setup wizard (doz ui), with doz onboard as the terminal alternative.