Since our Free Production Loops 2020 are delivered as WAV, REX, and unwrapped NKI's, you do not need to authorize the serial in Native Access. The purpose of receiving a serial is solely to authorize your download of the Loops in the Heavyocity Portal.
The serial you received automatically registers to your account on our site and in the Heavyocity Portal (where you will go to download your Loops) after your transaction. You can simply load the files into your host DAW on a track, or load the NKI's in Kontakt 6.4.2 Full version. The NKI's will not load into the free Kontakt Player, which is why we provide the Loops in WAV and REX formats.