I have added the Facebook login function though when I click it, it just said:
"Given URL is not permitted by the Application configuration: One or more of the given URLs is not permitted by the App’s settings. It must match the Website URL or Canvas URL, or the domain must be a subdomain of one of the App’s domains." If You are able to assist with this issue, I’d very much appreciate it!

Please make sure that you have inputted your website url in the Facebook app form correctly, namely https://www.[your_domain_name] , with the https instead of http, as you have added ssl (secured server) for your web hosting.

Also, here are the related User Manual topics on Social Login: http://www.ultimatewb.com/social-login

I have added the "s" to the HTTPS for the link on Facebook though the link on my site is still not working. I've looked over those other posts You shared and couldn't really find anything else about it.

Is there a working example of this feature that could be shown?

Facebook also gave me some codes to use though I don't see how I'm able to apply any of it within the admin panel since it seems most things use placeholders, I attempted to add the code to the text box on the Home page editing menu and it just appears as code - shouldn't there be a way to simply edit the html of any page rather than just adding placeholders? 

You don't need to add the codes for the Facebook Login to work, as it is a built-in feature in UWB Full.  But, if you did want to, you could do it by 1) Copying/pasting it directly on the page itself by clicking on the HTML button on the Content Editor Box, on the Add/Edit page, or 2) Copying/pasting the code into an Ad(d) (using the Ad(d)s Manager), and then copying/pasting that generated Placeholder Text directly into the Content Editor Box on the Add/Edit page where you want it (directly on the box, you don't need to click on the HTML button in this method).

We can check out your setup for you further if you email a jpg attachment of a screenshot of your Facebook app settings.  Also, please email your website admin panel url, username/password and we can check on your website admin panel settings for the Facebook social login.  Please email this info again even if it has not changed from your account setup/previous emails.