Sorry but WICED 6.2.1 does not support STM32L series processor. We had written a blog post https://community.cypress.com/community/wiced-wifi/wiced-wifi-forums/blog/2018/10/10/stm32f469-porti... to support a processor from STM32F4xx series but that already had a WWD existing in WICED for that series. That document could provide you some pointers to get started but in your case, further work would be required to support WWD for STM32L4 as well as peripheral drivers for the MCU.
An easier approach to add wireless connectivity to your system would be to use a wireless MCU with integrated host such as CYW43907 which would eliminate all the hassles of driver development.
