Since you are able to log into the forum it means you have a login into our system. Are you trying to use the same login with the XDK that you are using to log into the forum?
Try installing App Preview onto your phone and confirm that you can log into that using your userid and password. Also, see the items from this FAQ > https://software.intel.com/en-us/xdk/faqs/general#recover-xdk <
Also, see these FAQs:
The Intel XDK, and its supporting backend services, has been retired. See the first thread in this forum > https://software.intel.com/en-us/forums/intel-xdk/topic/722218 < for more details and see the release notes > https://software.intel.com/en-us/xdk/docs/release-notes-information-intel-xdk < for recommendations on alternative tools.