You may find that it is not possible to copy extracted text from the Document Viewer in Relativity. Even CTRL + C will not let you copy text that you have selected to the clipboard. This frustrating limitation on a function that is widely used in many applications, may be caused by a rights permission issue on the document object.
Ask the admin for the workspace to confirm that the group to which you belong has the local access option on the document object checked off. If not, you will not have the ability to copy on the document viewer.