If you have purchased license for Bentley LumenRT from Bentley Systems Run the licensetool.exe as admin as explained here:
1. Locate the "licensetool.exe" file on your hard drive, by default "C:\Program Files x(86)\Bentley\MicroStation V8i (SELECTSeries)\MicroStation" for SELECTseries versions) for example
2. Right click on it and select "Run As Administrator"
3. The License Management Tool will start, showing "(Administrator)" in the top bar
Once the License Management Tool pop up select in the activation status Bentley LumenRT and start with the activation process as you do with other Bentley products.(see screen shot)
Note: If you are not a Bentley licensed customer you should direct your question to e-on software by visiting the tech support page at e-on:
This article ->Go to the Troubleshooting Tips and the point 4. Manually activate MicroStation as administrator