I don't know what the rules are there. They're precharged and there's no requirement in my municipality to be qualified to install them as they are just more or less plugged in to a dedicated whip disconnect outside and the lines connected here after routing them and mounting the head indoors.
I noticed in my install manual, there is to be no radius in the lines smaller than 4 inches, but that was apparently too much to ask of the installer that put mine in. I wanted to put mine in on my own, but my room was being done by a contractor and he'd have nothing to do with that, so he had his usual HVAC sub come out and put it in. They did a nice tidy job other than missing that detail (I figured i'd give it a rest and not bother them).
The requirement here for the manual is to have a dedicated 20 amp 220v breaker to a whip disconnect (Varies by machine, I called mitsubishi to confirm that it can't be smaller or larger than a range as it's designed to keep the machine from being able to get in a situation where it draws tons of current and damages itself), and then the precharged lines are good for runs up to 25 feet. If the run goes longer than that, then the setup may need to be charged (high pressure, not older HVAC style system that most DIYers are used to here) to bring pressure back up. Most installs here are head inside the wall and outdoor unit just outside (as is mine) and no need to get close to 25 feet of line.
I did get to do the buying of my setup, though - contractor gave me a commercial only plumbing supply contact so I could get the bits at cost and then pay the contractor's sub and electrician. Total cost was half of what the authorized HVAC dealer was here.
8 years running every day so far for my system, no maintenance other than cleaning the filter in the head unit from time to time (in a woodworking shop, that would be more often, but about once a year here - the whole house filter in the furnace makes it so that there's not much dust).
Temp inside the head in summer is below freezing - it's wonderfully efficient without needing to make much nose or move huge amounts of air.
The generics now cost less than half what my system did - when mine croaks, I will probably not spend the money for a brand name system again, but will install it myself since the contractor won't be involved and the dedicated line /disconnect is already in place.
All of the time that the HVAC techs spent was making drilling brick look difficult and talking up how big of a deal it is to drill anchors into brick. And then they hadn't seen a mitsu system before so they spent over an hour playing with it "testing it to make sure it's working".