Hi Adam,
You are correct. The USB is for the GUI only and you do need an extra piece of hardware.
The documentation does not mention that you will need a LaunchPad (MSP-EXP430G2) with a 4-pin header soldered to J4. This will be added to the User's Guide.
Please see the link as an example: https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/38/DRV8308EVM_5F00_TEST.pdf
This link is for the DRV8308EVM but the concepts are similar. The connections are different.
Our apologies for the omission.