It is not mandatory to use that code. Indeed, many sellers do not use the app to run their seller accounts, and that is needed here for that code.
This is how to finalise that transaction now, you need to do this now, only on the Seller Hub here:
https://www.ebay.co.uk/sh/landing
Then, go to Orders >> Awaiting Postage, click on the item , then top left View Order details, on the right from More Actions drop down menu, Mark as Dispatched.
Dispatched is eBay's wording for a collected item.
If your payout is being held bbecause you are a new or returning seller, if the buyer leaves you feedback it can be released sooner, otherwise it may just be a 21 day wait.
