Just don't try to install it on a Mac M1. That won't end well.
For the retro designer, the legacy hardware operator, or the archivist, this build represents the last of the "lean" Creative Cloud era. While you would never choose it for a collaborative, cloud-native 2025 project, if you need to output a 200-page print catalog on a ten-year-old PC with zero subscription latency, there is still no better tool than InDesign 12.0.0.81.
was the initial "Gold Master" release of the CC 2017 line. Unlike subsequent updates (12.1, 12.2, and 12.3), this .81 build is unique because it predates the major UI tweaks that came later in the 2017 cycle. It is raw, responsive, and largely bug-free relative to the major features it introduced.