Hi fraccah and welcome to Forum!
I don't know Scoopex demo, but demos in general are quite picky. Some of them work if launched from Workbench, some of them need to be installed by WHDLoad (check if there is an installer for your demo here: http://whdload.de/download.html)
and the rest don't work with OS in background at all.
Your demo, especially if it's provided in ADF format, belongs to the last group, most likely. In that case, don't launch it from AmiKit desktop. In Windows, when, you run AmiKit.exe, click Configure, go to Floppy Drives and insert your ADF file to DF0 drive - it's like an inserting floppy disk to Amiga. Then launch emulator and it should boot that floppy disk.
But be advised, that AmiKit is configured as A1200 machine. If the demo is for Amiga 500, you probably need to tweak WinUAE settings a bit so it's closer to Amiga 500 emulation. For more info about WinUAE settings please check https://www.vware.at/winuaehelp/