Good news: There is no longer a three-export limit in the Starter plan for the desktop version of Premiere Rush – Adobe removed this limit in version 2.0 on November 15, 2021.
Basically, Rush on desktop now acts the same as Rush on mobile – the no-cost plan gives you unlimited video exports with a "freemium" model that offers use of most of the features and content.
If you want to use Rush's premium features and content in your exported videos, then that wouldn't be included for free and you'd need to upgrade to a paid plan. More details covered here:
Premiere Rush Free Download: What's Included in the Starter Plan?
But the basic Premiere Rush app is now free with no export limit on desktop or mobile.