Autodesk does not store versions older than 2018 today (this time next year they will drop 2018, they will drop 2019 the follow year, and so on).
Ask in the 3DSMax forum to see if any of your peers can offer a solution for you, otherwise you'll have to try websites on the web that sell downloads or disks of your old software AFAIK.
3DSMAX forum is over here
https://forums.autodesk.com/t5/3ds-max/ct-p/area-c1Good luck.