"The STM32F373xx embeds an USB device peripheral compatible with the USB full-speed 12 Mbs. The USB interface implements a full-speed (12 Mbit/s) function interface. It has software-configurable endpoint setting and suspend/resume support."
Best Regards.
STTwo-32
To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
Look under 'Documentation' for App Notes, etc; eg,
AN4206 - Getting started with STM32F3 series hardware development
AN4879 - Introduction to USB hardware and PCB guidelines using STM32 MCUs
Also look under 'Tools & Software' - check out Dev Board schematics, etc
A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.