1. Launch CMD Elevated
Click on Start and then type in CMD and right click on it and select "Run as Administrator".
2. Open Exchange 2019 ISO
In your downloads folder, double click on the Exchange 2019 ISO and take note of the drive letter.
3. Start running commands
In the cmd window, navigate to the drive letter from the previous step. Run the following command: Setup /m:install /roles:m /IacceptExchangeServerLicenseTerms - once the setup completes you can reboot your server.