I think I solved my problem.
The following test case will open URL#1, then it will open URL#2, and finally it will open URL#3.
The “0” (zero) in users.csv,0,URLForEachUser corresponds to row #2 (the second row) in users.csv. In other words, Katalon considers row #2 to be line zero. Obviously, that can be a little confusing but now you should not be confused.
The “1” in users.csv,1,URLForEachUser corresponds to row #3 (the third row) in users.csv.
The “2” in users.csv,2,URLForEachUser corresponds to row #4 (the fourth row) in users.csv.
Put simply…
Katalon 0 = row 2 in your .csv file
Katalon 1 = row 3 in your .csv file
Katalon 2 = row 4 in your .csv file
My solution above is based on the following comment by @Piotr
Thank you Pitor!