@Douglas Bonilla Thanks for posting in our Q&A.
The link you provided is ADE method. ADE method needs that the device is purchased in Apple School Manager or Apple School Manager. It seems that your device isn't.
There are only three methods to enroll MacOS to intune. Given this situation, it is suggested to use BYOD enrollment method or Direct enrollment method to enroll this device.
For BYOD enrollment method, devices are marked personal by default. You can add the Macbook serial numbers to the corporate device identifiers to mark the devices as corporate. For Direct enrollment method, you can use this method when devices are owned by your organization. However, they aren't associated with a single or specific user. For more details, please refer to the following article:
Hope it will help.
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