Frankly, I'd invest in the newest version of Photoshop, have all the available and up-to-date tools, have the option to use cloud storage, and get all of the features and benefits of the newest version.
You'll have a genuine Adobe product with their full support and guidance. The cost is relatively nominal at $9.99/month for PS photography plan. Why take the risk in the after-market of possibly pirated versions or versions you won't be able to register
I hold no prejudice against users of older software that they've purchased and owned and have been using since their release without the need/want to update. Heck, I drive a 15-year-old Civic coupe because that's all I need, it gets me from Point A to Point B, and is in decent shape. (My wife, of course, uses the 2-year old Nissan.)
But if you don't have the software and starting with a fresh application, why not take the safest and most recent offering? And have all the advantages of future updates as well.
It is your decision and no judgement made. Maybe you'd rather own than rent. In this digital environment, just do it safely and securely.