Looking for advice over possible approach for mesh development

Greetings from Bulgaria,

I am a bit new in game development but, I do compensate with enthusiasm and desire to develop skills in this direction :).

My passion is archviz and faced few weeks ago the ArchViz Explorer in UE asset store. Downloaded it and started to examine it.

After few days of research, I decided to look for help here. I would like to create similar base “floor” as the attached but with different “paths” on it. Currently I am struggling to understand how to create the paths.

EDIT: Looks like I can’t do attachments since I am new user. Still if someone is familiar with ArchViz - the asset, I am looking for is SM_Roads_01.