Answer by Jay Lee for Google Drive SDK: To copy files from a user to another user via Domain Super Administrator access right

Use domain-wide delegation to impersonate each user https://developers.google.com/drive/delegation.

Authenticate as source user and share file with target user https://developers.google.com/drive/v2/reference/permissions/insert

Authenticate as target user and copy source file to produce target copy of file owned by target user https://developers.google.com/drive/v2/reference/files/copy