I don't use Evri, but check your order details see if there's a code there.
Otherwise, you'll need to contact eBay Customer Services, hopefully they can provide this code for you.
To Contact Customer Services, I find the quickest way to contact them, either for a Live Chat, or you can select to speak and request a Call Back, to click on this link:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
On weekdays lines open between 8 a.m. and 10 p.m.
On weekends they open between 9 a.m. and 6 p.m.
Perhaps it's best to contact them very first thing in the morning when the lines first open, there's more chance of Dublin answering.
@brock6267