Turn 120 volts two plug outside into AC connection
For the 12000 btu unit you linked to it is 120v.
Are there any other loads on this outlet or circuit?
A 12000 btu unit normally draws under 15 amps with an inverter.
The one main concern I know about on these units are using a sealant like nylog blue to make sure the fittings do not leak. We had a class over a year ago they mentioned servicing these units the number 1 problem was leaking fittings.
I have not used one but would use nylog blue . No interest in the company I use the product.
As far as tapping that receptacle if nothing else is on that line I would feed a disconnect from the receptacle and use it that way.
As with all splits make sure to hang the unit level or slightly lower on the drain side. Do not kink the drain and cut the line off just above the ground.