Shortest path - taking obstacles and the terrain into account

Hallo,
I am so happy to have “stumbled” across this topic. I am searching for the best positioning of fire exits that need to be 60m. apart from each other in a Voronoi structure, or in other words How to position points with equal distances from one another on a graph network? Is it then a graph on a graph? I will really appreciate any clues! It is for a University project and unfortunately I can’t find no one to help me solve this. Here is a link to the topic where you can find the file.
Thanks in advance for even reading this massage!