select the version at the top of the left nav bar.
https://docs.microsoft.com/en-us/sql/ssms/download-sql-server-management-studio-ssms
src - https://stackoverflow.com/a/60114506
SSMS direct download
v18.7.1 (w/o debugger) https://download.microsoft.com/download/2/d/1/2d12f6a1-e28f-42d1-9617-ac036857c5be/SSMS-Setup-ENU.exe
v17.9.1 (w/ debugger) https://download.microsoft.com/download/D/D/4/DD495084-ADA7-4827-ADD3-FC566EC05B90/SSMS-Setup-ENU.exe
v16.5.3 https://download.microsoft.com/download/9/3/3/933EA6DD-58C5-4B78-8BEC-2DF389C72BE0/SSMS-Setup-ENU.exe
src - https://sqlserverbuilds.blogspot.com/2018/01/sql-server-management-studio-ssms.html
origin - https://www.pipiscrew.com/?p=19331 download-old-ssms-versions