The content submitter is supposed to update their item for the latest release so it’s a bit of an unfortunate situation if they just stopped caring or something. As for opening the content in newer versions you could open the 4.9 editor and then the content you bought if it’s in project format to convert it to 4.9. If it’s an assets you add to a project than add it to a project of the same version and convert that to 4.9. As for the 4.8 content not working in 4.8 you’ll likely have to find the thread related to it in the marketplace forum so you can get help from the content creator or other users directly.