ERROR: Unknown opcode '0x4D5A' — This is still an EXE. You’ve been tricked.
There’s no online tool that can truly convert an .exe (Windows executable) into a .dmg (macOS disk image) in a way that makes the program run on a Mac. That’s like trying to turn a diesel engine into an electric one by changing the label — the internal machine code is completely different. convert exe to dmg online
He dragged it to Applications. Opened it. The icon bounced once… twice… then a terminal window exploded with hundreds of lines of gibberish, ending with: ERROR: Unknown opcode '0x4D5A' — This is still an EXE