Mac System Requirements
Igor Pro 9 runs on macOS 10.13 - 10.14. Igor Pro 9 for Mac is only available as a 64-bit application.
Igor Pro 9 runs on macOS 10.15 (Catalina), 11.0 (Big Sur), and 12.0 (Monterey) but see this discussion of caveats and known issues.
Windows System Requirements
Igor Pro 9 runs on Windows 7 or later. Both 32- and 64-bit applications are installed by default.
Igor Pro and Linux
At the present time Igor does not run under Linux.
Some users have had some success running Igor via Wine and via CodeWeavers' CrossOver Office Wine-based product. You can read about their experiences by searching the Igor mailing list database for "Linux" or you can view a summary in the Are you porting Igor to Linux? article in the forum.
Igor Pro 9
Igor XOP Toolkit
Igor NIDAQ Tools MX