Outlet is a macOS application Since the idiots at Apple broke the Safari user agent string

Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)

under macOS Big Sur, the automatic detection of which version of Outlet you need to download is temporarily suspended and you have to manually choose which version you want/need to download:

Download for macOS 10.14 - 10.15
Download for macOS 11.0 (incl. support for M1)