Hello Gaurav,
As part of the installation process for the Android Support Package, several third-party packages are downloaded and installed, including the Android NDK. These packages are downloaded and installed from third-party sites, and there are occasionally issues where they are unavailable.
The best thing I can recommend is to ensure that you have stable internet and try again. Getting a direct connection over Ethernet is usually more stable than WiFi, which can help to ensure it isn't an issue with your connection. Try again at different times of the day if it still continues to fail.
I understand the frustration that these failed downloads can cause. We are looking into possible resolutions of this issue at this time.
-Cam
