Ambisonics is a full-sphere surround sound format: in addition to the horizontal plane, it covers sound sources above and below the listener.
Unlike other multichannel surround formats, its transmission channels do not carry speaker signals. Instead, they contain a speaker-independent representation of a sound field called B-format, which is then decoded to the listener's speaker setup. This extra step allows the producer to think in terms of source directions rather than loudspeaker positions, and offers the listener a considerable degree of flexibility as to the layout and number of speakers used for playback. (Wikipedia)
Below are a number of links to websites and videos that will explain the concept of ambisonics, what equipment is needed and how to setup a DAWs application.
How to playback ambisonics using Reaper article by Axel Drioli. (members only)
A detailed setup on how to configure Reaper to playback ambisonic recordings, including template and all necessary plugins to get started.