You need a single set, i.e. 540E/510E as offered here. After that you only need further 540E-Wlan Powerline adapters without the 510E adapter.

Attention, this is not a signal amplifier, but a device that connects a LAN signal (e.g. Internet) via a power socket to a second device and makes the LAN signal available from there. This type of connection is often called Powerline. However, Powerline does not work over separately fused circuits, so I doubt that it will work for 4 floors of a house.
If, on the other hand, it is WiFi (WLAN) that you want to distribute in the house, then you probably need more of a so-called repeater. Possibly even several, because depending on the construction of your house, one may not be enough.