Ok, so not the Webmail URL itself. I checked with my friend again, and he suggested our actual cloud host's URL of our team's website (cloud18.unlimitedwebhosting).
However, even after putting in this as the SMTP address and one of our website's email addresses and credentials ... no luck. Still "Server Not Found" when I try "discourse.[my_hostname]" or "discourse.localhost" in a browser. I think at this point, it's probably best I just list out some of what's in my app.yml file that I've been modifying manually:
Line 23: Changed http "80:80" to "10080:10080" (since I was getting an error before about 80 being in use, and one of the guides I read suggested to change to an unused port)
Line 48: DISCOURSE_HOSTNAME: discourse.nexus-matt.org
(my computer's hostname is "nexus-matt.org". When I type this or "localhost" into a browser, I get the "Apache2 Ubuntu Default Page" (since I've installed Apache on this machine), meaning that my hostname is recognized.)
Line 56: DISCOURSE_DEVELOPER_EMAILS: 'firstname.lastname@example.org'
(I figure I can put any email address here, right? Could I use an email from our team's webmail as a DIscourse Developer Email, or does is have to be a part of my local hostname domain?)
(Port 465 was what my friend suggested, for smtp-ssl)
I have not modified anything else in app.yml. I've followed everything (except the Cloud Hosting instructions) in this link: https://github.com/discourse/discourse/blob/master/docs/INSTALL-cloud.md
Well, I also haven't added "valid SPF and DKIM records in your DNS. See your mail provider instructions for specifics", but would that actually effect Discourse not showing up on my machine?
And yes, I'm well aware that routing configuration will not be covered on this forum. I just want to get Discourse up and running locally on my machine right now.
Also, is there any kind of error log that the Discourse laucher generates?