There is a possibility to download the latest server release of Adobe Campaign Classic v7. This provides an opportunity to set up a sandbox environment for learning purposes.
You can find all the files along with the client console installation under the software distribution. The only requirement is to have your Adobe ID linked to Adobe Experience Cloud solution. And this is exclusively available to Adobe partners. Check with your company to see if they have partnered with Adobe and if they can add your Adobe ID.
When all set and you have the access to download the installation files, next you can look on how to install the application server on debian.