Hello,

Your question of "I am not able to download question papers why" is not complete. You haven't mentioned the subject or the competitive exam that you wish to download the question paper for. Also, you haven't mentioned any particulars about the portal.

However if you fail to download, there might be a prbability that you aren't connected to a stable internet connection. Try to refresh and try again.
You can also check other sites on google to download question papers from.

Here are some ;links that you might find useful:

https://law.careers360.com/articles/nlat-answer-key

https://school.careers360.com/download/sample-papers/hbse-10th-maths-question-paper-2020

https://engineering.careers360.com/articles/jee-main-question-papers

Hope this answer helps.