Its generally not a great idea to use adb. The (likely much less secure) PC gets highly elevated privileges over the phone.
Can just connect the phone without adb and transfer files via MTP and the File Explorer of most desktop PC operating systems.
When/if you don't need to worry so much about phone security I think you should be able to push files to secondary users by using the correct path.
is the root of the owner user
Secondary users tend to start with
then 11, 12, 13 and so on
You can list your users with
adb shell pm list users