If you want to have your voice memos added to iCloud so that you can create a playlist in iTunes/Apple Music with them that is synced on all your iCloud devices, I've finally figured it out!
1. Get the voice memo into iTunes (I downloaded them from Dropbox, opened them in iTunes on my computer).
2. Convert them from m4a to AAC in iTunes (File> Convert> AAC). iTunes will create a new copy of the file in AAC, so you'll have two copies of the song in iTunes now-- one in m4a, one in AAC.
3. Click the triple dots to the right of the newly created AAC file. Select "Add to iCloud".
4. Watch the spinning circle in the top right corner, the file will show DOWNLOADED when it's finished. The dotted iCloud icon becomes solid. It worked!
5. Watch the song show up in your "Recently Added" section of iTunes/Apple Music on any of your devices 🙂
6. Add to any playlist!