The Minecraft 1.9 update changes the way maps work, and gives map makers more tools to create custom experiences in Minecraft.
Unfortunately, this means that most maps which feature command blocks (including all of our preset adventure maps) will no longer be compatible with Minecraft Realms. To prevent them from breaking, we'll be locking access to preset adventure maps once the update is released.
You can still download any affected maps for offline use before, or after, the update. If you’re not sure how to do that, check this support article.