Are you looking for some specific minor verion of Illustrator 25 or you are looking for versions earlier than 25. If the answer is later then you won't get those versions via Creative Cloud, as Adobe only supports the latest two versions and that would be version 25 and 26.
Now if you are searching for some specific minor version of 25 and not getting it via Creative Cloud you can contact support and ask them for a download link, they might be able to help you with that.
To contact support. Login to your account and navigate to the URL below. Make sure that the browser has cookies enabled, and all script blockers are disabled. https://helpx.adobe.com/contact.html?rghtup=autoOpen Type AGENT to avoid bots and talk to a human. Also, be mindful of answering anyone who sends you a private message. See the following for more information about scammers https://tinyurl.com/y7cfrr7y -Manan