@hpardess, the Medication Mangement UI module has been discontinued. In its current version, the module is not recommended for production use at all.
In order to be able to add a drug in the list, you need to first have it created as a normal Concept (of class “Drug”) and then create a Concept Drug that links to this concept by going to Administration → Manage Concept Drugs
From there you can create new drugs, linked to drug class concepts. It should then appear in the drug list in MMUI screens. If not, you may need to rebuild the index, such as explained here: Drug dispense and administration in OrderEntryUi - #10 by mksd