This is the required hub.
It comes with everything needed to run an AMS.
If you require the drying features of the AMS 2 Pro, you need the additional switching power adapter
I understand your confusion as despite making the A1 series compatible with the AMS family, they appear not to have updated much in regards to the store listings and ease of access to all the related printers.
It is technically possible to use an existing P or X series buffer or hub as others on the forum have found.