Adobe’s numbering system, naming and split of Lightroom to Classic and CC does add some confusion to the mix. LR 6.4 and 6.8 are actually Classic CC (it was called just CC at that time, but is not the CC of today), they are from 2017 I believe. It was October 2017 when we got the two different versions and at that point Classic was at 6.13. Those will not accept XMP presets, they require LRT presets.
In April of 2018 Adobe switched to XMP from LRTEMPLATE. At that point we had Classic 7.3 and CC 1.3, these are the oldest versions of Lightroom that will accept the XMP presets. Anything newer than this will work just fine. These versions will also accept the LRT presets, though the install process is different.
If you are not subscribing to Creative Cloud, then your version is most likely not new enough for XMP presets. If you are subscribing, then we need to check version number to make sure you are at 7.3+/1.3+. LRT presets will install in any version of Lightroom.
Accessing Lightroom via your internet browser is NOT the same as having Lightroom installed on your computer. This is simply another way to access the Lightroom Mobile app.
AI presets are only available in XMP format. These presets rely on the most up to date technology. We recommend making sure your Lightroom install is update prior to using AI presets.