Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
For me this happened when tried to download fw for the board STM32F207ZGTx. After switching to another board, STM32F072RB, I was able to download and install the stdPeriph firmware. It seems like my board is not supported.