This is one of those tasks that you tend to forget. After you create reports in Microsoft SSRS you need to assign assess to users in your domain. A common way of accomplishing this is to assign these via a Windows domain user or group. Most users will need the Browser role that allows them to view your reports. You can assign this at a folder... This is one of those tasks that you tend to forget. After you create reports in Microsoft SSRS you need to assign assess to users in your domain. A common way of accomplishing this is to assign these via a Windows domain user or group. Most users will need the Browser role that allows them to view your reports. You can assign this at a folder level or to individual reports. The folder allows permissions to be inherited to all reports under that directory.
To assign the Browser role perform the following procedure below which assumes that your report management url is <your-server>/Reports
I did this via the following procedure

• Got to http://<your-server>/Reports
• Click on the Properties Tag
• In Security click on the New Role assignment button
• Type in the User or Group name preceeded by the domain (i.e. DOMAIN\username)
• Check the Browser role
• Hit OK

That's it.

Read more http://billennis-ssts.blogspot.com/2011/04/ssrs-browser-role-assignment.html