So when I go on the PiHole Admin website, I should be able to whitelist a domain, blacklist a domain, and more right?
Actual Behaviour:
Instead, it gives me an error when I attempt to whitelist a domain, blacklist a domain, even regex filters. This happened when I just finished setting up my PiHole, before I put in a bunch of scripts to try to block YouTube ads.
You are running Apache2 as the web server. This is an unsupported configuration. But, here in Community Help other users can help you make this work. Or, you can use the supported lighttpd web server
[80] is in use by apache2 (https://discourse.pi-hole.net/t/hardware-software-requirements/273#ports)