June 13, 2021
Full disclosure: I am an Offensive Security employee. This My-CMSMS walkthrough is a summary of what I did and learned. Friends from #misec and I completed this challenge together. No company restricted resources were used. Creating walkthroughs for Proving Grounds (PG) Play machines is allowed for anyone to publish. However, PG Practice machines from the paid tier, are not permitted to have public walkthroughs posted.
On June 11th, @InfosecAli and I signed into Proving Grounds and booted up an intermediate PG play machine called My-CMSMS.