First open

Open Velto on your Mac.

This beta isn't notarised by Apple yet, so macOS asks you to allow it once. It takes about a minute.

Open Velto.dmg and drag Velto to Applications.

Open Velto from Applications.macOS says it can't verify Velto. Click Done.

Open System Settings, then Privacy & Security.Scroll to Security. Next to “Velto was blocked”, click Open Anyway and enter your Mac password.

Click Open Anyway once more.