The main purpose of an ATS (as name suggests) is to do just the tracking, some of them do parse resumes to fetch key data points while others provide an online application form where you have to fill-up the details. Keeping a standard resume (Fancy stuff is good for in person, use a straightforward one on online applications) and Filling up in-depth details on online forms really helps.
In context of applicants, the job of ATS is to make scoring interviews harder.