If you're looking for a free alternative to Vuforia, consider XZING. The free version works with Unity and allows you to find image targets in the real world. Check it out here:
So basically, you register and download the free version for Unity. You get a ZIP file, and once extracted, copy over some of the folders in the Assets directory as specified in the documentation here:
Note: Don't copy over anything not in Assets directory.
Follow the rest of the documentation and you should be fine.
I wanted to set up my own camera as in the sample scene and spent hours trying to figure it out. Finally I got it, and here is the solution:
Make the Camera work for XZIMG Augmented Vision
Go to Lighting Settings:
Copy settings from the sample scene provided by XZIMG