Each version of Daylite is compatible with specific versions of macOS and iOS. Our website has an overview available here.
Why can't I see the Daylite Mail Assistant on macOS 10.14 or newer?
How do I update the Daylite App on macOS?
Can I run the plugins I used with Daylite 4 or Daylite 5 with Daylite 6 as well?