There's a version on a large site on the internet that claims to be legal -
but I've no idea if it's "legal" abandonware or not. Of course you'll still need either a real Amiga or an emulator, and the emulator will need a Kicstart ROM, and that certainly isn't abandonware.
If you don't have a real Amiga, I'd suggest getting Cloanto's
Amiga Forever - you get tons of ROMs, emulators, Amiga-PC networking software, a pre-configured workbench, help and more.