I'm no expert. but that looks like it would be difficult to repair as the plastic locating extrusion has snapped and there are bits missing. Breakers yard or ebay maybe?
Have a look at this:
https://translate.google.com/translate?sl=de&tl=en&u=https://www.zroadster.com/forum/threads/deckel-von-armlehne-demontieren.120609/post-2745908