I bought the S3 Terios controller and it's connected with Bluetooth to my PC (Windows 10). The right side doesn't work, but it does work on my phone.
Diablo 3 on PC does not have controller support. Blizzard has stated several times that they are not planning to add this in the future.
While you are certainly free to ask again, Blizzard has repeatedly said they have no plans to add controller support to the PC.
Most likely, your controller is working fine on PC. You can test the buttons in the Control Panel, in the USB Controller tool.
There are several tools available to improve controller input for games like Diablo 3 (e.g. games that do not have built-in support), such as XPadder. These often rely on mimicking keypresses or mouse movement with controller input. Explaining exactly how these tools work and how to best set these up for Diablo 3 is outside of the scope of this answer, and is something best researched on the internet. There are plenty of resources available.