When i received the EBB36* of BIGTREETECH i slowly built up all the connections towards my existing hardware of the Ender 3v2. One information that was missing was the stepper pinout. The manual  specifies the port as “E-Motor” but doesn’t show the details. You could derive it from the schematics  but still isn’t very visual.

I finally found it here  on github:

| B2 | B1 | A1 | A2 |
|_   ___________   _|

Or more visually (please crosscheck the colors with your extruder of choice!)