Great question. The unit is pre charged for 25 feet of lineset . I was right at the limit for my install.
I installed the lines, did all the vacuum related work. Then just cracked the valve on the unit to distribute the refrigerant.
I had a bottle of refrigerant on standby from a buddy. Didn’t need to use it . I was going to get the EPA cert, if my buddy didn’t exist. I heard it’s super straightforward