If you are using Maya, this video is a quick guide on how to bake ambient occlusion to textures to then allow it to be exported as glTF from Unity.
A few things to note:
- Needs to be baked to 2nd UV
- Unity will not show the AO (Ambient Occlusion) correctly, but it will come into Plattar fine
- Export the FBX file out of Maya and then into Unity (OBJ will not work)
- Only use these (below) fields when exporting to Plattar