I have High Sierra and the latest Winclone 6 that’s supposed to be compatible but when I try to open it I get the message This version of Winclone requires 10.12 or earlier. Please contact twocanoes.com for an update." What’s up with that. My apologies if this has already been addressed.
It is possible that you are opening a older version of Winclone or it didn’t get installed correctly. Try doing a “Get Info” in the finder on the app and try reinstalling.