You may need to get a text from the URL and place it on the Guest sign-in page. For this, we have created some Java scripts to look up the URL string.
This is just an example and your requirement may need some modifications to achieve what you need.
First of all log into the guest admin section of ClearPass (https://IP/guest)
1) Expand administration and select plugin manager:
2) Scroll down to Galleria Skin:
3) Select Configuration
In the section Guest Content Header, insert:
const queryString = window.location.search;
const urlParams = new URLSearchParams(queryString);
const siteParam = urlParams.get('site')
document.getElementById("site").innerHTML = siteParam;
4) Insert URL Code
This code must go before the Java script or it will error out:
<span id="site">