Hi, Did you get installed the report builder from the adobe analytics tool section?. you should also have the respective access to use the report builder. I suggest you to check with your project admin and get the relevant access for the same.
I'm running into the same issue, and I have all admin permissions. It is possible that this is an issue with the latest release of Report Builder, as another computer I have is running an older version of Report Builder and isn't having any problems.