Because the official source is gone, the search results for "photoshop cs4 trial download" are now a digital minefield. You will find plenty of sites offering the file, but here is what you are actually risking:
If you have a legitimate, paid CS4 serial number from back in the day, you can contact Adobe Support. They have a legacy downloader for paying customers who need to reinstall their old software. You cannot get the trial this way, but you can get the full version you paid for. photoshop cs4 trial download
It is important to understand the current lifecycle of Adobe software: Because the official source is gone, the search
If you need photo editing software but do not want to pay for a modern Adobe subscription, there are excellent alternatives that are safe, legal, and compatible with modern computers. You cannot get the trial this way, but