Just take a look here, and you will find many of the Cascade Amiga efforts, which made the group quite famous on Amiga between 1988 the 1991. Amongst them are multifile demos (so called megademos), music collections and single file demos/intros.
All Amiga stuff listed here is archived in the following file types: .zip, .dms, .adz or .adf. All these different file types can be loaded in UAE by simple "drag'n'drop" them into the emulator window (in case this is not possible it's mentioned in the description). Keep in mind, that an Amiga Emulator will need a kickstart rom. More info here.