It tries to update itself and I get Download Failed.  I even installed the latest version with the same issue.  Uninstalled/Installed only for the NI circle jerk to continue.  This issue was reported on the NI forum in Sept. and no answers. Oddly enough the old Service Center still works but can't add a library that way.  I don't know if Microsoft did something or it's NI.  Meanwhile purchasing any library for Kontakt that needs a serial number is off the table. 

This seems to be a general issue, probably at the NI server end. NI forum has a few reports of this - 
https://www.native-instruments.com/forum/threads/native-access-gives-a-download-failed-message.322208/ 
 
jdf
 

It's fixed now...I had the same issue

I should've figured that out when all machines it didn't work.  I thought there was a possibility a Windows f'update might have screwed it up.
 
I'm not a fan of how NI is doing things.  Native Access blows compared to Service Center. Yo use to drag and drop a library and then you could enter the serial # - done.  Development seems to be in regression these days.