In Pro Tools, when you create an Instrument, Audio, or Aux track on which you'd like to instantiate MachFive, MX4, Symphonic Instrument, Ethno Instrument, or Electric Keys, make sure that the track is stereo. If the track is mono, you won't see our instrument plug-ins. (Surround versions MachFive can be instantiated on quad, 5.1, and 7.1 tracks.)

Also, when choosing the instrument plug-in, make sure to look under multi-channel, not multi-mono.