I tried to add my Fidelity account to my Quicken Starter program, but no data was downloaded
Starter only has banking accounts. You cannot do investments in Starter. You need at least Deluxe.
if you are interested in a basic system - for banking and investments - you might take a look at Quicken Simplifi - which is a Quicken online web based product -
https://app.simplifimoney.com/