So I finally got to try it out yesterday and the whitelist feature works. Here is a guide on how to use it. I will to most of the images since the image will be shrunken or cut off on my blog.
First go to https://192.168.208.1:445
You must enter this exactly and FYI for anyone who might stumble upon this and use it you must use YOUR machines I.P. so the format would be https://xxx.xxx.xxx.xxx:445
You should be at the homepage of the machine. Press connect and you will be prompted to enter your user name and password.
When you press connect it will look exactly the same except now you're logged in.
Now mouse over services and click on URL Filter
Now you will have a large webpage with a lot of options. I myself don't know what all of them do but for now we just want to restrict peoples access to the web. Anyways...
You should immediately be able to see 4 large boxes. The second row of boxes is for your whitelist. In the first box enter the websites you want to ALLOW your clients to be able to access.
Make sure the "Enable custom whitelist" option is enabled.
Scrolling down you will come upon two more boxes. In the first you are able to give certain machines unrestricted access to the interwebs. Here is an example.
You might have noticed next you can change what appears on the block page like message, image or a redirect. Change them as you please.
Lastly remember, REMEMBER under advanced settings
Make sure that "Block all URLs not explicity allowed" is checked. Caused me quite a bit of grief. Once you're done with that press Save and Restart and you are done.
Now if you want to make this easier on yourself at the very bottom of the page you can create a backup of all your URL filter settings which get saved to your computer. This makes keeping multiple settings easy when you have a complicated setup like certain unfitlered IPs, scheduling, whitelist, etc.
All you have to do to restore your settings is under "Restore URL filter settings" press browse, find the backup and press "Import Backup File"
If necessary I can learn how to use the scheduling feature and make a guide on it.