This is the most stable method for macOS 10.15.7. Do not download the desktop app. Use the web client instead.
WhatsApp Desktop app (Electron)
Don't stress about the lack of a native app. On an older OS like Catalina, running WhatsApp in a dedicated Chrome window is often lighter on your CPU and battery than the official Electron-based desktop app ever was. whatsapp web mac os 10.15.7
Tap the Menu (three dots) > Linked Devices > Link a Device . iPhone: Tap Settings > Linked Devices > Link a Device . This is the most stable method for macOS 10
: Point your phone camera at the code displayed on your Mac screen. Supported Browsers & Requirements whatsapp web mac os 10.15.7