I have a String where i want to find the string between quotations, for example: My name is "Carl". I want to return the string Carl, not "Carl". I'm using the regular expression "(.*?)" but the result is "Carl". What should I use? or how can i take those quotations after match the substring?

Make sure you aren't looking at the whole match output. When you use subexpressions you need to grow the node downward to expose those results. Also, I think "(.*)" is all you need. I don't think the extra ? is doing anything. BUT, if your use case is this simple, I would probably avoid using the Match Regular Expression node. It is very heavy weight and is known to sometimes cause problems with EXE builds. paul_cardinale probably has the best solution.