Rhino will function fully for 90 days in free trial mode.

To download on a MAC, go here:

https://www.rhino3d.com/download/rhino-for-mac/6/evaluation

To download on Windows, go here:

https://www.rhino3d.com/download/rhino-for-windows/6/evaluation

Then, complete the following steps:

1. Enter your email in the blank box (it is safe to do so) and click next to download. 
2. Go to your email and open your "Welcome to Rhino 6" email. If you do not see it in your inbox, please check your trash/junk/spam folder. The email will look like this
3. When installing, you will be asked for a license code. This code is in the email above. Copy and Paste this code to complete the installation.