The requirements say
When using Workforce in the office with the web app, or in the field with the mobile app, you must have an ArcGIS organizational account and be a level 2 member. Project owners need to be administrators or publishers in the organization to create Workforce projects. ArcGIS Online and ArcGIS Enterprise 10.5.1 or later are supported.
I assume all are met and the license level is appropriate?
Yes, but it doesn't really have to do with Workforce. I'm trying to install Data Store and configure it on my AWS server. When going through the config, it doesn't let me choose relational, which is what I want.