If I'm reading that correctly, it's relying almost entirely on blood pressure and heartrate in addition to BMI for the initial screening -- there's also the "two questionnaires", but it's not specified whether they're assessing anything beyond "personal parameters for such criteria as height, weight, heart rate and blood pressure".
It's not something I know much about, but based on a quick Google, RED-S can result in low blood pressure and heartrate, but they're not a given, and it sounds like they may only occur in more severe cases; the IOC paper just calls them "potential indicators":
https://stillmed.olympics.com/media/Documents/Athletes/Medical-Scientific/Consensus-Statements/REDs/IOC-REDs-CAT2.pdf
But based on the flow chart, if your BMI is in the normal range heart rate and blood pressure aren't abnormally low, you won't be screened any further.