Many Facebook Files
Message
Too many files for facebook platform in use.
Explanation
Facebook has a limit of 100 files per build. in order to run on the Facebook platform, your playable must be within this limit.
Steps to fix
Decrease textures or videos usage to stay under the file limit. To see all the used textures, please go to the Size Breakdown tab as shown below. You can also create Texture Atlases (Or Sprite Atlas) so you can use a single texture file for multiple GameObjects. More information can be found here.