Source code and binary packages for Regina 7.3.
Here on GitHub you can find ready-made packages for macOS and Windows.
GNU/Linux packages are handled differently - for these, see the Downloads section of http://regina-normal.github.io/ .
A sandboxed macOS version can also be downloaded directly from the App Store (for free). See the Downloads section of http://regina-normal.github.io/ for links, or just search the App Store for "Regina for 3-Manifolds".