Exporting to the .vsdx file format is currently under development.
Architectural differences in the .vsdx and .drawio modelling formats, on top of functionality differences between Windows and browser-based rendering engines means your exported diagram may not render identically the same as the original diagram, or interactive behaviour attached to diagram elements may not fully match.
Fore more general info on draw.io for Confluence or Jira, please refer to our draw.io webpage.
And some great blogposts! Blog - draw.io