Fixing “created in a newer version”
It is the most common block in the Adobe family: the project is not broken, it was just made in software newer than yours. There are only two ways out — upgrade your software, or bring the project down to something your install can read.
Find out which version you actually have
The warning usually says “newer version” without naming a number. Your own clue is the version you have installed — open the About dialog and note the main version number. That number sets your ceiling: the downgrade target has to be that version or older. Picking something newer is pointless.
Two routes, two different costs
Upgrading is the least effort, but it drags your OS, GPU drivers and plugins along with it, and old plugins may not run in a new release. Bringing the project down leaves your environment alone, at the cost of losing whatever features only the newer version had. In a team there is one more thing: upgrading is a decision you make alone, downgrading is a decision that has to work for everyone.
It still will not open after downgrading
The usual reason is that the target was still too new — if you run 2021 and picked 2022, the result is still unreadable to you. Second, make sure you opened the newly generated file and not the untouched original.