Vulcan Beta incompatible with Compatability Mode

My computer is older and the only way for me to play RS3 has been in compatibility mode. Heard the Vulcan beta was released and wanted to test it out. Opened the Launcher, clicked play, and hit the cog in the bottom left of the loading screen and changed my graphics settings to Vulcan. Closed out and reloaded the client.

Clicked play in the Launcher and now the loading screen just closes. I try clicking the cog but the interface does not stay up long enough to change back to Compatability Mode before closing. I tried uninstalling and reinstalling the Jagex Launcher but same problem.

Am I just unable to play unless I get a new computer?