Group enrollment is the most commonly used option in SimpleMDM. A group enrollment URL, when used for "enrollment by link" or enrollment with Apple Configurator can be reused as many times as you wish.
A group enrollment URL is specific to a device group in SimpleMDM. All devices enrolled with a group enrollment URL will join the device group that the URL is associated with. Administrators can optionally move devices to different device groups at a later time.
One-Time Device Enrollment
One-time device enrollment URLs allow an administrator to create a device in SimpleMDM before the physical device is enrolled. This has the benefit of allowing an administrator to pre-configure certain options, like email accounts or device-specific app assignments before the device is enrolled.
One-time device enrollment URLs can only be used once. After a device has enrolled with the URL, the URL is no longer valid.
Which is Right For Me?
Since one-time device enrollment URLs are for one-time use, using them does not scale well. We recommend using the group enrollment method unless one-time device enrollment is required.