I have dowloaded the file and then put it in the mods folder. Did not work. I also tried to put in in the resurce packs and it did not show anything. I have Dowloaded Fabric API and Fabric. Please tell how to dowload this Dupe hunting mod.

Make sure that you are using only fabric api and ui utils in the mods folder, and be sure that fabric has been completely installed.
There are no resource packs required.