Nobody can make possible what is impossible. CS4 is discontinued and no longer supported. You must choose which is more important to you.
1) Either downgrade your OS and never, ever upgrade your computer again.
2) Install CS4 on a 2nd older Mac computer.
3) Or buy modern software to go with your new operating system.
Creative Suite is no longer legally sold by any vendor, retailer or country.
MODERN OPTIONS:
Photoshop or Premier Elements 2020 (approx $100, no subscription needed)
https://www.adobe.com/products/photoshop-elements.html
Creative Cloud Photography Plan (approx $10/month for 1 year subscription)
https://www.adobe.com/creativecloud/photography.html
Creative Cloud All Apps Plan (31 + apps & services)
https://www.adobe.com/creativecloud/plans.html
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Beware of fake Adobe reps who may contact you privately offering to sell you software or take control of your computer. It's a scam, run away!
https://tinyurl.com/10791730