need my Apple Customer Number, but Apple Business Manager service is so poor

So, I am building a start up, and created the business account, got it verified and approved, through the many calls with them I was never told I cannot buy devices directly from apple web site, so I went and bought our macbooks, and setup mosyle business as my MDM, now that I am going to setup the devices I need my Apple Customer Number, I cannot find it anywhere, so I found this on Apple's web site:

If you buy Apple devices from an Apple Store, ask the Business Team for your Apple Customer Number.

But apple customer service, told my I won't be able to add the devices I bought on their own web site and need to cancel the order and wait until someone can call me to work out how I can get the apple customer number, honestly, the idea of a business manager portal is to simplify things, specially for small teams