Since Brexit UK clubs can't sign foreign players under 18 any more (don't ask me for the full details of why as I don't know them, just know this is the case) and as that side is quite a young side it means there aren't many overseas players included. Great for future Home Grown Player quotas...
There were still tickets available on Monday: https://www.northstandchat.com/threads/u21s-vs-dinamo-zagreb-u21s-weds-17th-jan-19-30.405880/#post-10976383