Read MIDI data from Akai MPK mini mkII USB MIDI controller to AVR
USB MIDI is a different protocol that is not supported by the FT232R.
You would need to use a general-purpose microcontroller with USB support.

Furthermore, USB makes a strict distinction between hosts and devices, and your controller is a USB device, which can be connected only to a USB host.

So you would need to use a board with a USB host (or OTG) controller, such as the Raspberry Pi. Alternatively, pay for the Kenton USB MIDI Host, or connect both the controller and your AVR board to your PC.