Using REGEX at Filter rows Step

I have seen this option at Filter rows step, but where should I place the Regex expression for that REGEX filter to work?

Here’s a Sample WF to do this provided by Support team.

WF_FilterwithREGEX.psw (16.3 KB)

Can I use a parameter or variable inside the Filter Row as a string to be used in the condition?
In this case where the word “salvar” is written?