I got my serial number, but the installer is failing because the directory they are trying to access is far too long.  File paths like that don't work in Windows.  I might be OK if my Native Instrument content directory was closer to the root.  But it's not.  So sick of these Mac-centric, non-testing developers that appear to have no clue how the world works.
 

msorrels
I got my serial number, but the installer is failing because the directory they are trying to access is far too long.  File paths like that don't work in Windows.  I might be OK if my Native Instrument content directory was closer to the root.  But it's not.  So sick of these Mac-centric, non-testing developers that appear to have no clue how the world works.
 

That explains the few errors I saw but it did not stop the installation. Looks like certain previews wont be available. Hopefully they will sort it. I will check the NI forums tomorrow.

So the Preview installer is a giant 8gig ISO, which Native Access downloaded.  I mounted it and ran the installer by hand. 
 
Oddly enough when doing it that way the suggested install location was the User Public Documents folder (instead of the directory I have configured in Native Access).  But even more interesting is the suggest directory name was NBPL instead of the fully spelled out "Native Browser Preview Library" that Native Access forces you to use. 
 
I pointed it to a drive with storage for 8gigs of previews and a shorter path.  The install took awhile but completed without errors. 
 
If you use the fully spelled out "Native Browser Preview Library" and put that at the root of a hard drive, the longest filename ends up being 253 characters long.  Which is almost too long as it is.  260 is a hard limit but practically anything longer than 247 can be a problem.  But if instead of "Native Browser Preview Library" you use "NBPL" that path ends up being only 227, which gives you enough room for a sub-directory or two and still stay under 260.
 
By installing it by hand and setting the install dir I put it in L:\Content\NBPL without any failures.
 
 

Looks like the 8gigs of previews includes products I don't even own.   Looks like previews for every NKS instrument.

Looks like I don't want to waste 8 gigs of drive space.

8 gigs? No way, José.

Well its going to take a bit of space for a preview of every NKS preset going but the utility it adds to browsing is very useful. Getting an idea of of the sound of a preset before loading the instrument is going to be a huge time saver, particularly with large Kontakt libraries or looking for sounds across multiple VSTi's.


I will uninstall and do a manual reinstallation with a shorter path later.

msorrels
So the Preview installer is a giant 8gig ISO, which Native Access downloaded.  I mounted it and ran the installer by hand. 
 

Where did you find this? I have uninstalled and want to reinstall manually but I think Native Access has deleted this file after installation?

OK - Just checked the NI forums, looks like the issue is fixed
https://www.native-instruments.com/forum/threads/native-browser-preview-library-windows-installation-issue.321845/
 
I will try a regular Native Access installation!
 

On their forum they announced they have renamed the product in Native Access to just "Previews" which will reduce the path requirement a bit.  Doesn't actually fix the problem but it certainly makes it work for a few more people. 
 
To figure if this will work for you, in Native Access take the Content Location setting in the preferences and count how many characters it is, then add 229 (that is the length of the longest path plus 1 for the leading slash and 1 for the NULL at the end).  That will be the longest path the current installer needs.  260 is a hard limit, so with the new "Previews" name your Content directory path can't be more than 31 characters long.  My current content directory for NKS/Library instruments is "G:\Content\Native Instruments", which is 29.  Here's one of the longest file name (there are a couple of file names with this same length in the install)
 
 
"\Previews\Samples\d98e97c2-a913-407d-bb67-00532c24b11a\Instruments\_Stereo Mixes_\_Advanced_\Individual articulations\d - High Strings Half Section\.previews\d - High Strings Half Section - FX 4 (Cluster Swells) (Stereo).nki.ogg"
 
Add that to your Content directory.  If that total length is under 260 you may be OK.