The short answer is... yes!
Please note, STEMS are sub-mixes (Bob explains this in the video below).
If you want a folder containing every single audio track (including midi audio) for your song, you need to request MULTI-TRACKs.
The easiest way to get access to your STEMS or MULTI-TRACKs is to discuss and plan for this to take place within your session time. If you request STEMS or MULTI-TRACKs months later, well after your session, files often need to be retrieved from the WhatStudio archives. This takes additoinal time, and therefore incurrs a recall fee if required quickly (otherwise, delivery is at the discretion of What Studio's timetable).
...so, you are strongly recommended to request your files on the day of your session. Do it at the time, it sooo much easier, and fresh, and done.