You may be running out of free space. Check the free remaining space on your hard disk.
Otherwise, there may be something preventing Genymotion Desktop to download the template OVA from our servers.
Make sure that your firewall/antivirus/network allows the following:
- Outgoing TCP port 80 and 443 on *.genymotion.com
- Outgoing TCP port 80 and 443 on *.geny.io
- allow genymotion.exe and player.exe to communicate with vboxmanage.exe
If neither apply to you, you may need to completely remove and reinstall Genymotion and VirtualBox.
See How to uninstall Genymotion Desktop completely (purge)?