The normal manfrotto handle has a 6mm thread. So you have to change the 1/4" thread inside of the Adapter to a 6mm thread. I just "screwed" it inside softly and everything worked nice with the new 6mm thread. The plate has to rest against the Bottom of the Tripod with a tube between Adapter Plate and tripod.
I found a small tube normally used as curtain accessory which fits nicely. H: 15mm , outer diameter 18mm, inner diameter 12mm = 3mm thick "wall". There is a flat screw inside on top, I opened up the hole with 6mm. This screw centers the tube on the 6mm Tripod Screw. Fixing the tube to the tripod with the Adapter Plate on top, you can easily fix the leveling top.
Workflow to fix the Tripod Adapter: First fix Top Plate with loose level plate of tripod. Then center the lower NN adapter to 3/8" screw of adapter plate, fix the tripod head by using the adapter plate. Move the pole upwards to fix it to the center column.
For the other type of center column without leveling top, you have to get this sort of adapter: