Theelgirl's DueUtil is part of the 2.0-Mortal branch of clones, though it is the only remaining one from that branch. It is owned by Theelgirl#4980, and has been alive since October 3rd, 2018. Due is usually updated every month or more, with minor additions and bug fixes in between. You can contact the owner through Discord by joining the support server with the link in the !help command, and DMing her, or by asking questions in #support. If you really need help, you can use !requestsupport, and someone should join soon to help you.