I'm having trouble getting infrastructure on a planet, as there seems to be no option for a freighter to load infrastructure.
Do you have the infrastructure built?
If yes, then in the order tab of the TG menu, you highlight the planet they were built, and scan the list of various good. Its generally next to installations. Then make sure you select an amount to carry, that does not exceed the cargo capability of the cargo TG.
Each 5k cargo hold can hold 2 infrastructure.
I've notice instatillations no matter the planet cost don't really have a sizable population limit until they are in the triple digits. Generally I try to get six thousand built and shipped to a planet to hold a pretty okay population.
Currently, I have a TG of ten 25k cargo ships transporting infrastructure to Titan. Its taking for fucking ever. Almost two years of constant trips they are almost done transporting the six thousand worth of infrastructure.
You can also have the infrastructure built then set up supply and demand order for the civvies to /eventually/ do it. The civvies will also eventually ship in more infrastructure as a trade good that will be added to the planets infrastructure.
I thought about leaving enough infrastructure on my home planet to act as a global bomb shelter.
Then I'm looking at my overally large pop of 5 billion, and realize that I would probably need several million infrastructure to do so, if it got really bad, with the nuclear winter and some of it being destroyed in the bombardment.