It may be a collection of "dry" vocal stems or loops intended for use in a Digital Audio Workstation (DAW) like FL Studio or Ableton. "a928" (The Identifier):
Check the manufacturer’s site or official forums (e.g., Yamaha for VOCALOID, or GitHub for open-source synthesis).
"A928" is a model number occasionally associated with older consumer electronics or MIDI interfaces. A .rar file with this name might contain the drivers or firmware required to make a specific device "sing" (communicate) with a modern PC.