I am using LR CC 2015 on windows 10, 64 bit. I just went to process a batch of photos. During the setup of the export I created a directory to save the files to. The system prompted me for Admin rights. I confirmed. The export failed because the user of LR (my email address for Adobe) was not the same as my username on my PC. I had to add sharing to the folder to that email address to get the export to complete.