Add devices to ABM without reseller

This is a user-to-user forum—Apple are not here, and we have no support capability for ABM, ASM or other special Apple initiatives.

.If your are the ABM point person in your company yo ushould have cotact informatio for support. If your are not that person, try here:

You cannot add macOS devices that were purchased from a seller that does not support ABM to the service. You need to purchase your devices from Apple directly or an Authorized Reseller that supports ABM enrollments (these include CDW, IT1, B&H Photo, Adorama, MacMall, and more). Contact the seller to learn more.

It is not clear what you are asking. Are you asking how to add your Macs to MDM?

MDM overview for Apple devices - Apple Support