4.9 was just released not long ago and the content creators need time to update their content to the newer version, I believe they have around 45 days to do so. That said it is only a matter of time until they are all compatible with 4.9, and if you purchase the content it will be automatically updated via the launcher and you will get a little !] icon to let you know there is an updated version available. Some of the content is compatible but doesn’t say so yet like some of the environment packs I know are because they are mostly non code-reliant assets, its really blueprints and things that may be affected by changes in the version’s underlying coding that need updating.