I have several interactive maps made with Web App Builder, which I've embedded into Storymaps. I'm hoping to include something like the initial pop-up in the link below (where the background is greyed and instructions are given for navigation, background information, explanations...)
NatGeo Mapmaker Interactive

I know I could make a cascade storymap to explain navigation, and then embed that in a separate adjacent tab (tabbed storey map) before the interactive map, but I was hoping for something more streamlined.
Does anyone know how I can approach this? Thank you
(More information - I am hoping to embed this into 1. a web app builder-made interactive map, as well as 2. a Tour Storymap)