Your citation is in reference to what allows F1 visa holder to be considered for residency status after 5 years. "You will not be an exempt individual as a student...for any part of more than 5 calendar years, ..."
The substantial presence test as described in IRS Publication 519 U.S. Tax Guide for Aliens is a test of 3 consecutive years, beginning with the first year of consideration and counting back as in this example:
Substantial Presence Test
You are a resident for tax purposes if you meet the substantial presence test for calendar year 2020. To meet this test, you must be physically present in the United States on at least:
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31 days during 2020; and
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183 days during the 3-year period that includes 2020, 2019, and 2018, counting:
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All the days you were present in 2020, and
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1/3 of the days you were present in 2019, and
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1/6 of the days you were present in 2018.
2020 in your case doesn't apply as your five year of exempt status are 2016 2017 2018 2019 and 2020.
IRS Publication 519, US Tax Guide for Aliens
