If you go to the report and click on the cell, choose "TextBox" Properties. There is an "Action" option where you can specify an hyperlink with an expression. Refer below link.

https://weblogs.asp.net/rajbk/Contents/Item/Display/87

By refering the below article i have created the sample. Based on the Contact name you need to do the task what you want ie download or display document based on the querystring value.

How to create RDLC report step by step in ASP.Net using C# and VB.Net

The report will not render because hyperlinks are disabled by default in the ReportViewer control. To enable it, add the following in your page load event.

ReportViewer1.LocalReport.EnableHyperlinks = true;

Screenshot