SSBM ISO not working

SSBM ISO not seen by slippi-dolphin emulator as ISO when searching for it in dedicated file. changing it to all files it shows up as type 7Z file when selected it reads "This does not seem to be a copy of Super Smash Bros. Melee. Please use regular Dolphin (https://dolphin-emu.org/) for running games other than Super Smash Bros. Melee. I would very much like for this to work for me to play melee online.