Only officially licensed third-party products can be loaded in REAKTOR PLAYER. Check with your REAKTOR product's manufacturer if your product is "Made for REAKTOR PLAYER". Usually you can find one of these logos on the product's page:
These "Made for REAKTOR PLAYER" products can be installed with Native Access. Read this article for detailed installation instructions.
Instruments and effects that are not made for REAKTOR PLAYER require the full version of REAKTOR to run.
Please note you will need at least REAKTOR PLAYER version 6.2.0 to load third party products "Made for REAKTOR PLAYER".