For models / textures / animations I’ve used the “migrate” functionality in the unreal editor to move content from the marketplace into Ark. Just create a new Unreal project and import your marketplace content. Then right click on the folder, select “migrate” and select the mods folder for the ark devkit as the target. Depending on which engine versions you content is compatible with you may need to recreate some materials but it’s a fairly easy process of opening the graph in the unreal editor and recreating it in the Ark devkit.