I was wondering when it said , no paid for assets, if every asset was made in Blender by that person can they enter ?
You can use assets that you create in Blender. You can also use assets you create in other programs like Maya or Plasticity (paid programs). The point is that you are not to use assets you spent money on directly.
Edit: Some services like MotionArray.com have subscription fees that open up libraries of content like sound effects and music, among other things. Even though you don't pay directly for specific assets, because you are paying to get access to a curated library of assets, I don't think you can use those, though you might have to ask the organizers about that to be sure, if that's something you'd consider doing.
If you create your own assets you can definitely use them, but you will have to provide them with your project as well.
Using external applications to generate models or images is perfectly fine, even if they're commercial tools. You would have to export from Maya to some file format you can import into your game engine of choice anyway and provide those asset files. So if you had your model as an FBX someone who doesn't own Maya may still import it into Blender if they wanted to...
As for subscription services... pay attention to their licensing. The assets you get from there most likely do NOT allow redistribution, so they're out!
If you used for example textures.com and paid for higher resolution versions and included them in your finished build, you could still list a link to which textures you used and someone who did not pay might get the lower resolution version of it instead. the game might not look as good, but would still be fully functional (more or less, depending on what the texture images were used for)...