I am a pro user of ultimate-guitar.com but i am not able to download guitar pro files of the songs for offline learning
Can you please be a little more specific?

For songs where it is a Guitar Pro file, at the bottom right of the tab (to the right of the stars for rating) there should be a blue "Download Guitar Pro Tab" button that you are able to click. Do you not see this?

Also, keep in mind that Tab Pro and Guitar Pro are two different things; Tab Pro is a UG service, whereas Guitar Pro is a separate product, and we happen to host a large number of tabs in the Guitar Pro format.

My God, it's full of stars!