How to turn it on and set it up... its plugged in but nothing is happening. is there something that i need to download to open the camera?

You can just plug your CAM313 on the USB port on your PC (Windows), or Type-C to USB adapter (made by Apple) on your iMac.
Then select CAM313 on the Video Device on your Zoom, Skype..etc. Please see the below video:
 
How to set up CAM313 and use Zoom in macOS and Windows:
 
macOS

 
Windows

 
In case you want to adjust the video quality, you can use our CamEngine:
Webcam Service | AVerMedia