They are two separate products and none are available for desktop versions of PD. You can check on
DirectorZone for user-created stickers and there are also sticker-like PiPs in various
content packs.
You can request that stickers be made available for future releases of PDR from File | Rate Us & Provide Suggestions, however I think it's unlikely that PD19 would be updated with new features at this point.
For now, get the project started on the mobile app and add your stickers then try exporting it to the Cyberlink Cloud or Google Drive. Then import it into the desktop version and continue editing.