YuMe doesn't work

i am new to unity and game developing and i saw this tool YuMe to help build maps, i have the free version, now when i open it in unity all of the block and stairs and everything doesnt have color, its all pink and i cant seem to fix it.
anyone knows how i can fix this?

 

You are probably using URP or LRP. So it's a shader issue.
Change your shader to the proper shader.

https://www.youtube.com/watch?time_continue=10&v=nB0r0c-SIVg&feature=emb_logo

 

When you import 3D models in Unity, it's not unusual that you have to create and assign materials manually.