MCP2210 - Plug n' Play HID Keyboard
USB devices never send anything on their own. To operate, they need a driver on host side to initiate transfers. 

In most cases with odd bridges the USB devices are designated to "miscellaneous class" 0xEF, and need a device driver to start communications/device configurations. Usually MCHP supplies these drivers that need to be installed. Then these bridges use proprietary interface to get actual data in and out. 
That's why you need a library of various API calls on host side, and write an application that uses these calls to communicate with USB bridges as MCP22xx.

The MCP2210 bridge uses HID class as its basic interface, and thus it uses standard OS drivers, with no need of MCHP proprietary drivers.  That's apparently is their definition of "plug-n-play". However, conformance to HID class doesn't mean automatically that it is a keyboard, it can be mouse, or joystick, or barcode reader, so you still need their tools and libraries to configure the bridge and send/receive SPI data.