1. Use the following link for downloading https://www.bentley.com/en/support and
2. Press Go to portal
3. From there you will access https://connect.bentley.com
4. . Under My Supports-> Click on Software downloads (You need to log in using your Credentials as Select User)
5. Type Bentley LumenRT in the search box
6 Click on the Download
7. Select Save as to place the file in a Specific folder or directory.
8. Run the installer
Note:"The activation period is now 7 days with the CONNECT Edition and other products released after September 1. This will improve the accuracy of usage data for every account. The activation period will be consistent across all products".
How to activate LumenRT
LumenRT 2015 free trial version now available for download