My Windows and Epic Launcher are installed in SDD C:, I moved the VaultCache to another hard drive E: using this method:
https://wiki.unrealengine.com/Troubleshooting_Launcher_Problems
My SSD C: only has 18GB free space. When I tried to download the KiteDemo, the launcher complain insufficient space at C:\Program Files\Epic Games\Launcher\VaultCache, however the VaultCache already moved to E:, that has 1.1TB free space.
Can I force Launch not to check free space?