Having a texture seam issue after atlasing

I am working on a map of sorts for a game that uses the unity engine (VRChat)…
Before atlasing (when the materials for each texture were seperate and not one material) there were no seams between the ‘tiled’ textures in this map.

Now that I used the CATS Plugin to join these materials into one and make them become an atlas, there are visible seams on the mesh with the texture atlas applied… I don’t know what to do.