Hi, what purpose does the scratchpad in draw.io serve, please?
The scratchpad in draw.io is your individual shape library. The scratchpad lets you add shapes to it. The shapes will be there for you whenever you need them in order to you create your diagram.
Please take a look at this blog post for more info on this feature: Scratchpad – Your helper for individual diagramming needs
Fore more general info on draw.io for Confluence or Jira, please refer to our draw.io webpage.
And some more great blogposts! Blog - draw.io