Platform
A few problems are specific to a particular operating system or IT policy.
macOS — “Loach can’t be opened” on first launch
You opened Loach for the first time on macOS and macOS blocked it, saying it cannot be verified or comes from an unidentified developer.
The Loach build is not Apple-notarized (ZTCS doesn’t subscribe to the Apple Developer Program), so Gatekeeper doesn’t recognise it and shows a warning on first launch. Open System Settings → Privacy & Security, scroll to the bottom and click Open Anyway. You only have to do this once; in-app updates afterwards do not re-prompt. (Update bundles themselves are cryptographically signed with the project’s own Ed25519 key — a separate check that runs on every in-app update, regardless of notarization.)
macOS — Intel Macs
You’re on an Intel Mac and the .dmg won’t run.
Only Apple Silicon (M1 and later) is supported. There’s no Intel build.
Windows: “Credential Manager access denied”
Saving keys or app-lock credentials fails on a managed Windows machine.
Some corporate group policies block apps from writing to Credential Manager. Loach cannot store secrets without it. Ask your IT admin to allow Credential Manager writes for the Loach process, or use a personal machine.