A downloadable version of RealFlight Drone is not available. Installation is only supported from an original DVD ROM. To install RealFlight Drone on a computer that does not have a disk drive, you can use an external USB DVD ROM drive. The RealFlight Drone disk is not referenced for daily operation, so you can store the disk once the installation is complete.
This option may be helpful to you: Several users have reported they were able to install RealFlight Drone from a USB flash drive. For that to work, you will need to place the disk contents in the root of the flash drive (do not place the disk contents in a folder). You will also need to rename the flash drive with the same name as the installation disk (RFDRONE_1). If you do try to install RealFlight Drone from a USB flash drive, bear in mind this method is not officially supported.