This situation generally appears for win10 users , which is caused by win10 system restrictions on the software drag and drop ,win7 also have a small number of users will appear.
So please follow these steps to troubleshoot the problem:
Step1: Turn off UAC:
Go to Control Panel
Change User Account Control
then restart the computer
Step2:If you still cannot drag after you have restarted computer,please double click desktop icon "Foxrenderfarm Desktop".Don't right click it by running as administrator
If the situation is still exsits,please contact our RD.