I wrote up these FAQ for PC recently, maybe one of them will help you. It sounds like it might be the 3rd one though.

Q: The client won’t load, or just opens in WinRAR!

Solution: If you do not have Java installed, first download and install it. Then right click Launcher.jar, navigate to “Open with > Choose default program”, and select Java as the default application. Finally, check [√] the box that says “Always use the selected program to open this kind of file”, and click OK.

Q: Even with Java installed, the client won’t load or gets stuck fetching data.

Solution: Delete the RSCR cache and redownload Launcher.jar from our download page. To locate the RSCR cache on Windows, navigate to C:\users\yourname\.rscrevolution and delete that entire folder. To locate the RSCR cache on Mac, open the Go To menu in Finder by typing Command+Shift+G, and navigate to ~/.rscrevolution and delete that entire folder. If that still doesn’t work, make sure your version of Java is current and that RSCRevolution.com is not blocked by your firewall.

Q: I have Windows 10 with the current verison of Java, but it still won’t launch.

Solution: You will need to create a batch script to execute the Launcher. Simply create a new Notepad document, and paste the following code there: “java -jar Launcher.jar” (without quotes). Save the file as “rsc.bat” (without quotes) and choose “all files” for the save-as type. Now the client should launch when you double-click the rsc.bat file.