Can I export legacy Rock Band titles directly into Rock Band 4?

No. You must first export legacy Rock Band titles into Rock Band 3 for your account to be validated as an owner of this content. Only then will it be available for free re-download in Rock Band 4 within the same console family as we make that content available. Please keep in mind that you must sign-in with the original account that purchased the exports previously to be able to re-download this content in Rock Band 4.