First go to Settings (bottom left hand corner) -> User Settings -> Personal Details. Then click 'Test default folder access'.

If a little success message doesn't appear, you can try creating a new folder on your desktop/documents called 'Anima-temp' (you don't need to store anything in this folder). Then click 'Select my own folder' and then select your 'Anima-temp' folder. Then test it again. Once you see a success message, scroll down and click 'Save changes'.