For years, macOS users studying for CCNA or CCNP certifications had to rely on VMWare or VirtualBox to run the Windows version of Packet Tracer. It wasn't until Cisco released Packet Tracer 7.x (and solidified it in version 8.x) that a native macOS application became a standard offering.
Minimum 4GB (8GB recommended for larger, complex labs). cisco packet tracer mac os x