to access private message sent by mcafee moderator;
if you are logged in to this community you should see an envelop/mail icon next to your username at the right upperside of this page.
when you click on this envelop/mail icon you will see the private message overthere.
click message to open and below is a reply button when opened.
if for some reason you don't see this envelop/mail icon change browser to Edge of Firefox.
another user from this community had this issue and changing to Firefox for example solved the issue.
myself using Edge and no problems.
hope this helps.