Size * count = number of bits per report:
0x75, 8, // Report size = 8 (bits)
0x95, USB_CONFIG_HID_TX_SIZE, // Report count = 16 bits (2 bytes) USB_CONFIG_HID_TX_SIZE=64
0x75, 8, // Report size = 8 (bits)
0x95, USB_CONFIG_HID_RX_SIZE, // Report count = 16 bits (2 bytes) USB_CONFIG_HID_RX_SIZE=64
The host PC and device should send all data in 2-byte reports.