Since Anti-tile makes use of procedural noise and complex mapping, the final result can only be seen in rendered view. Textured view will still display regular tiling. 

Anti-tile works with any engine that uses cycles nodes for materials.
Currently this includes:

• Cycles (2.79 + 2.8)
• Eevee (2.8)

The Anti-tile script to create Anti-tile textures is only guaranteed to work within blender. Therefore if you wish to use it in other engines you will need to apply Anti-tile in blender and then export out the material.

Yes! You can bake the texture channel of an object to an image and then save the image. However this output is not seamless, it is a static image (Blender just bakes what is visible) so once you bake it, you cannot procedurally change the size anymore.