How can I use my CS4 Design Premium? [CS4 Activation Servers are Dead]

No longer supported is not the same as cannot use the software. Just means Adobe will not assist you with any CS4 issues.

If you're on a Mac running Catalina or Big Sur then you're out of luck. Anything else, then follow the steps for Windows below.

If you're on Windows, install CS4, enter your CS4 serial number (which I assume is an upgrade) then enter your CS2 serial number when prompted. CS4 should install and activate and you can then use it.

What is your computer?

CS4 will not run at all on a modern Mac, and probably will not run on a Windows 10 computer

What is your EXACT problem... are you trying to install, or will your old programs not run?

When you ask a question you always need to provide some basic information
-Forum quick start https://community.adobe.com/t5/Community-Help/ASK-Forum-Success-Guide-Efficiently-using-the-forums/td-p/4791542
-https://community.adobe.com/t5/Get-Started/Questions-you-need-to-answer-to-receive-better-help/td-p/6199470
-https://community.adobe.com/t5/get-started/how-to-post-and-get-your-issue-resolved-or-what-do-you-need-to-know-to-solve-my-issue/td-p/11178657?page=1