step 1 = go back to Steam Fuse and export the base character as an Obj into a new folder
step 2 = go get the 4 (includes the optional detail map) map from the Mixamo Fuse teenA folder... note you have a Mac so the path is a little different to me because I use Windows
step 3 = import the Obj as a new character into Adobe Fuse, give it a name | tags and pick MaleFitA as the base edit then then put the 4 maps you got in step two as the order my screenshot shows... thats it, done