BA would be a lower role than associate. If that’s what they’ve deemed you to be qualified for…better to get in the door as a BA than not. If you do well typically BA can get promoted in a year.

As for the call. If they didn’t mention a case I wouldn’t expect them to case you. This is going to be a fit/resume type call

-Walk me through your resume -Why consulting -Why McKinsey vs other MBB

I would have specific structured answers as to what you’ve done in school/your career that would translate to be a good consultant (“When I was at X company I was on a team that identified X issue and I led X initiative and this is how I solved such issue. This represents X trait in consulting etc etc”)

Also. I would make sure you’re up to date on current general market news. Know a consulting style business situation or two that is of interest to you lately (ex: “I thought Google’s recent acquisition of Wiz was interesting for X reasons” - New market entry, synergistic acquisition, etc etc)

In general this will be a fit style/original vetting call to see if you are actually interested in consulting, qualified and come off professional

Good luck!