Using powerline adapter with different brand routers

I have asus routers in mesh. I want to buy a set of powerline adapter and use it 3 floors down. I read the description and I saw the following:

Note: Powerline adapters must be deployed in sets of two or more and be connected to the same electrical circuit. And TL-PA411 KIT is compatible with all routers and other powerline products.

Is it true that I can use it with other brands?

What does mean same electrical circiut? One room? Can we say that the main electric panel of the apartment is working like a switch? Can we say that from the main electricity meter of the apartment everything after that is one circuit?