Lol

Well, that's weird.
I do have put the .nav inside the map folder alongside the bsp of the map, and when I launch the map, the nav mesh does appeared.
And yes, I do have auto generated the navmesh, so there's are part with weird flaw

When i opened the map, i couldn't see a navmesh, either you talk about AI nodes or you compiled the .nav file into the map bsp, which doesn't work, it should be put in the maps folder along with the map. Also since id assume yours might be autogenerated, it will have flaws whereas mine i fixed those flaws such as invalid doorway connections and jump areas which nextbots couldn't use.

I wish i could have made ladder meshes too but it appears you used func_ladder instead of the ladder tool texture (with the exception of the one at the combine barricade)

Hey, gm_toxicair creator here.
Placing the .nav file inside the addon doens't work ? Because I already built the nav mesh, or maybe I'v done something wrong in the process