Thanks for your response, Pooja!
Since your client has created the Question Bank, it looks like he/she has shared this with you so you may view and use the questions in the bank in your courses.
By default, everyone is set as a Viewer of the Question Bank when shared with the team. As viewers, you can only view question bank and folder contents and use questions in your courses.
If you'd like to edit the questions in the bank, you'll need to ask the owner of the Question Bank to change your permission to an Editor, so you can modify questions and question banks, and rename or duplicate folders and subfolders.
See more details on managing question banks and assigning roles and permissions for folders here:
Hope this helps. Let me know if you have additional questions or clarifications. We're here to help!