Before you can use the software, you need the appropriate hardware interface to link your radio to your computer. The Programming Cable
This is where 90% of users fail. You cannot use a standard USB-to-serial adapter with the GP518. Motorola used a proprietary logic level. Motorola Gp518 Programming Software
The easiest solution: Mail your GP518 to a two-way radio shop. For $10-$20 per radio, they will program any frequencies you request. Search for “GP518 programming near me” or use online services like Radio Service Center or Atlanta Radio Repair . You ship the radio; they return it programmed. Before you can use the software, you need