Connecting appartment buildings pose a very specific challenge that is related to how WiFi signals propagate over the air, and how they relate with obstacles.
The LibreRouter is designed for long range links in between multiple nodes and short range links with devices that can be at line of sight with the node, or that not being at line of sight, are in close proximity to a node.
In an apartment building in order to build a neighbourhood mesh network you need line of sight, so you would usually fix the LibreRouter node on the roof of the building so they can connect to other nearby LibreRouters and build the mesh.
As those that are in the first floor will be too far from the node to get WiFi signal from the node, the best approach is to run cables from the roof down to each floor and on each floor to run again cables to each of the apartments that will be part of the network. Once you are inside the appartment, they can setup a home wireless access point.