This Link will help you with the list of all the companies and their links which provide USB drivers. Please note that some companies may not be listed in this list. In that case you may have to go to the respective website of the company and search for the particular device driver.
As you are saying that you have enabled the USB debugging
mode in those devices. Check whether they are connected properly. open the command prompt and type:
adb devices
The result will give the list of the connected devices. If the device can be seen in the list then you can be sure that its connected properly. And you can install the app directly on the device by typing in:
adb install path_of_the_apk_file/your_apk_file.apk
But note that you can only install the app in this manner not debug it.