Hello,
It sounds like you might have WebGL disabled in your Chrome settings - gSender uses Electron which is just a Chrome shell, so the settings there can affect it.
Which browser did you use to access https://get.webgl.org/ to see the spining cube? Firefox, Chrome, or something else?
You can check your Chrome specific settings by visiting (inside Chrome) the “chrome://settings” address.
At the bottom of the menu on the left, open the “Advanced” tab and click on the “System” option.
Make sure that the " Use hardware acceleration when available" is selected.
You can also visit “chrome://flags” and make sure WebGL is enabled on some older Chrome versions.
Restart and see if that makes a difference.
Past that, it might be that the driver for your video card needs updating. Those are the two places I’d start at least.