From their documentation panel:
A free version of the plugin is available to use for as long as you like, but has a few limitations. Firstly, you will not be able to customize your sitemap. Secondly, any audits run will only return results for your homepage.
Does provide some useful information when scanning the home page, but would be nice if it would scan more than one page. (Sure, you can change your home page to some other page and re-run the scans.)
It would be a little better if the Audit Results page started out with the "View By Issue" rather than "View by Page" (since it's scanning just one page). This flummoxed me for a minute, but then I could see that I had Alerts for: Color Contrast, Heading Order, Landmark One Main, and Region.
Oddly, though, when I added two "role=main" landmarks (using Elementor's Attribute panel), and this tool caught the problem (having more than one landmark) it didn't show me where the problems were, just indicating it was in the HTML.
Color Contrast: It found right away and showed me what elements had that problem.
This also creates a Post Content type of "wcag_scan", which showed up as an option in Yoast SEO maps.
I can imagine that this would be useful if you need to convince a client that you have passed inspection, by signing up for the paid version and then you've got a nice looking report to show.
The export function is pretty nifty, gives you a chance to view the report in Excel.
This is most useful if you have more than one page.