This is the list of errors that can occur when you are trying to export your level:
There should be no cameras in the scene.
There is more than one level in the scene.
There are no level objects in the scene. Check Example scenes.
SpawnPoint not defined on level.
There are no lights in the level. Check Example scenes.
There are no FallTriggers in the level. Check Example scenes.
There is no LevelPassTrigger in the level. Check Example scenes. (Check the number in your checkpoints scripts)
Checkpoint missing.
Dream Title cannot be empty.
Dream Description cannot be empty.
Invalid metadata.
Dream Image required.
All game objects must be children of the level object. Check Example scenes. (All thing must be inside "level") Check the images below
