Newer versions of Raspberry Pi Imager may sometimes fail to install on older devices. Also, new updates may not be fully compatible with some Mac architectures. While the developer fixes the problem, try using an older version of Raspberry Pi Imager. Previous versions of Raspberry Pi Imager can be found in Uptodown's version history, where the app's available files are stored. Safely download previous versions of Raspberry Pi Imager for Mac.