I have been involved with several installations of the Mitsubishi mini split HVAC. I install the circuit and disconnect for the outside unit. I typically install a 14/3 UF cable to a 60 amp disconnect with GFCI receptacle installed in the disconnect. The GFCI takes care of the required receptacle for AC servicing.
The units require 240 volts and a 20 amp breaker. However, the instructions state that it is okay to use #14.
The HVAC people take care of the rest. FYI, remind the HVAC people to install a disconnect switch at each inside unit. They try to avoid this since it is not a pretty sight. I have seen inspectors fail the mechanical inspection due to the lack of the disconnect.