Hi Neha,
I am able to download the file when logged in to SCN, there are a few re-directs which you need to patiently follow.
It is a 278MB zip file with Tool kits, Samples etc.., check with our local IS team on zip file download restrictions if any.
If your download is corrupted or something, try linking/bootstrapping the library from the external link as described in the link below,
The SAPUI5 website linked below, provides you with more info on tunneling the IE XMLhttp request - which I hope you will encounter,
UI Development Toolkit for HTML5 (SAPUI5)
With regards,
Ponilango P