Status of "NotNow" in Systems Manager Event Log
The error message “NotNow” is seen in the Event Log on an iOS/macOS device's details page when an action cannot be performed because the device is locked with a passcode. These actions include pushing managed apps, installing profiles, and other actions. When this occurs the device will attempt to re-connect with the MDM server as soon as the device is unlocked in order to retry the action.
The device should update on its own the next time the device is unlocked; no special action is required on the part of the administrator.
For more information on the "NotNow" status, including a list of commands that can be run regardless of a devices lock state, reference Apple's "Handling NotNow Status Responses" developer documentation.