It's very, very simple.
There are four teams (RRQ, TLN, T1, NS), so we use the four-way tie breaker (map differential) to put RRQ in 1st.
Then there are three teams (TLN, T1, NS), so we use the three-way tie breaker (head-to-head) to put TLN in 2nd.
Then there are two teams (T1, NS), so we use the two-way tie breaker (head-to-head match score) to put T1 in 3rd and NS in 4th.
That's how these tie breakers work.
You're not looking at how many teams there are in the tie and then going down the respective list. You're trying to narrow down the number of teams in the tie by removing teams from it. We had 4 teams, so we narrowed it down to 3, and then to 2.