Timer STM32 #error This code is designed to run on STM32F/L/H/G/WB/MP1 platform! Please check your Tools->Board setting
The Roger Clark's STM32 core  you're using is not currently supported. I don't know in the future if I can add that core into the supported list.
You have to use this Arduino_Core_STM32.
Convert to new core by following the intructions in Getting Started