Moving Library from one external drive to another

For over ten years I've had my iTunes library (movies, tv, home movies, music) on an external drive. I've just setup a new M4 iMac and as part of this have decided it's time to get the library moved over to a new drive as the old one is starting to make noise. With an new SSD formatted, I moved all of the library content from the old drive to the new drive without issue however while I can see all the content listed in AppleTV, I can't play any of it (as it says the content can't be located). Believe I've missed a step, e.g. creating or moving the iTunes Library.xml file perhaps?

Anyway, would appreciate any step-by-step anyone can offer to set this all right. Thanks