Doesn't sound right to me but to make sure why don't you download one of the free apps that show drive space on your Mac and what's using it? Here's three apps that you can look at. Only Daisy Disk is not free.
I think we’re ignoring the obvious - why did you download that app? Doesn’t sound reputable to me. Especially because it’s showing Xcode taking up 13GB but you need to “unlock” to see the 71GB. Hmm.