Here’s the catch: from My Esri for new licenses. It’s considered Mature Support (retired as of March 2022).
It is important to distinguish between and ArcGIS Pro . ArcMap is the traditional 32-bit application that uses the ".mxd" file format. While Esri has shifted its development focus entirely to ArcGIS Pro (which is 64-bit and uses ".aprx" files), they still technically support ArcMap 10.8.2 (the final release). Version 10.5 remains a popular version because it is stable, widely used in older institutional archives, and runs well on older hardware. arcmap 10.5 download