steam ffxiv online starter edition and ffxiv: shadow bringer standard edition, no stromblood expansion.
bought a redmage skip to lvl 70 from the store. the book and stuff was delivered. but when i try to use the book, i get "Unable to read Tales of Adventure. You must have the Stormblood expansion data installed and registered"
Have you actually registered your Shadowbringers key from Steam onto the Mogstation? If you right-click the game in your Steam library there is an option for "CD keys" and from there you can get the Shadowbringers key.
Then head off to the Mogstation, and there's a place to enter the expansion code.
After that, restart your game (if it's still loaded) and it should download the expansion and then work once you can log back in.