The ATS matches your resume against the job description and looks for the percentage of the match. The ATS kicks out SO many applications that it has little to do with how qualified you are and everything to do with how well you have matched the job description's keywords.
I can explain further if anyone wants. At this point, I ought to teach a clinic on it.
1. Have a basic resume template that you tailor to every resume before submitting it.
2. Most ATS do not recognize variants of a word. If the word in the description is "create," then you can't get "credit" for using "created" in your resume.
3. Use the cover letter to flesh out any gaps, and now there's a different cover letter style that gets more attention.
4. Make sure there are absolutely no typos. Use Grammarly and an extra pair of eyes. If you don't have extra eyes, read it backward. Grammarly Premium is a great idea for those letters you type to parents too.
5. There's a site called jobscan.co that you can use to match your resume to the job description. They give you a few free ones, but the subscription is ~$90 for three months.
I'll check back here later if anyone wants some help.