
Success! Thanks Einstiensboi from sparing me the "Set Names" problem, but I poked around and I think I just overlooked something insanely stupid and simple.
So it all hinged on the "database name" field. Instead of just leaving it as is ("modx"), I included the special prefix my server uses.
I.e. instead of just leaving it "modx" i put "sulman_modx" which is the exact name of the database I manually created. I also changed the prefix field to "sulman_" since that is the prefix used by all my databases. That seemed to do the trick. Hope that helps someone.
To summarize:
1. Manually create a MySQL database for Modx via your CPANEL or whatever other system you use.
2. Add a user to that database and give it all privileges.
3. Run the ModX installation from your browser and follow prompts.
4. Input the following info:
Database host: localhost
Database login name: [Your loginin name from Step #2]
Database password: [Your login pw from Step #2]
Database name: [the FULL NAME Of the DB you created in #1...so for me it was sulman_modx]
Table prefix: whatever the prefix is
5. Click "test" and you should be ok!!