Hi @Daniela William,
Only the latest two versions of the Creative Cloud apps are supported and available for download. Now since version 2022 is the latest version so the only options available for download would be CC2022 and CC2021.
Regarding prodesigntools, it provides download links directly from the Adobe servers and Adobe has stopped sharing public download links for apps since CC2019 so you won't find the download link for CC2020 on this site. Now for the solution, contact support and ask them to provide you a download link for CC2020 app, they will provide one if they can. This is the only legit way to get the installers now for CC2020. If the support does not provide you the download link and you can't upgrade your MAC then cancel your subscription before you get charged a cancellation fees.
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.
Type AGENT to avoid bots and talk to a human.
Some links for your reference
For refund rules, refer to the following link.
Look at the following link for information on how to cancel your subscription.
Also, be mindful of answering anyone who sends you a private message. See the following for more information about scammers