Margin has no accounts, so no demo credentials are needed. Open the app and start writing.

Two entitlements may look worth questioning, so here is why each is there:

com.apple.security.network.server is for the Google Drive backup. Google's installed-app OAuth flow
redirects to a loopback listener on 127.0.0.1, which is the only flow Google still supports for a
desktop app, and the sandbox refuses to bind that socket without this entitlement. Nothing listens
on a routable interface and nothing accepts a connection from another machine.

com.apple.security.network.client is used only to reach googleapis.com for that same backup. The
backup is optional and off until the user connects their own Google account. Nothing else the app
does uses the network: writing, the page preview, spelling, grammar, and every export run entirely
on the machine.