Can anyone tell me how to access old cloud files?

Are you talking about files created with Adobe programs that were saved to the Cloud, or are you talking about Adobe programs that are older than 2019?

Someone else can probably help you if it's the first (data files created with Adobe programs that were saved to the Cloud).

If it's the second (Adobe programs older than 2019), the answer is those are no longer accessible.

Adobe instituted an N-1 policy about midway through 2019. Access to CC programs is now limited to the current version and the most recent previous version, and since CC programs are all on subscription, you can have 2020 and 2019 versions installed but anything earlier is not available.

As I understand it, if you have a pre-2019 version installed, it remains unless you uninstall it. If you uninstall it, you can't get it back. (I could be wrong, YMMV, caveat emptor, and no doubt someone will be along soon to tell us both if I am wrong about this.)