AutoPlay must be turned off for non-volume devices.
Allowing AutoPlay to execute may introduce malicious code to a system. AutoPlay begins reading from a drive as soon as media is inserted into the drive. As a result, the setup file of programs or music on audio media may start. This setting will disable AutoPlay for non-volume devices, such as Media Transfer Protocol (MTP) devices.
How this relates to the STIG checklist: STIG vs SCAP benchmark.