We can use cleint_search.xml API and search client info using its username, it willl provide complete association history.
Syntax
https://<server ip>/client_search.xml?query=<username>
We can list all the folder using folder_list.xml but output provides only client count but not complete details
Sample output of folder_list.xml for folder id 18
https://<server ip>/folder_list.xml?id=18
<amp:amp_folder_list version="1" xsi:schemaLocation="http://www.airwave.com amp_folder_list.xsd"><folder id="18"><bandwidth_in>6293349</bandwidth_in><bandwidth_out>7950469</bandwidth_out><client_count>2</client_count><down>1</down><mismatch>6</mismatch><name>Aruba-Lab-TME</name><parent_id>1</parent_id><up>11</up><vpn_client_count>0</vpn_client_count></folder></amp:amp_folder_list>