Contributions page not found 404

Any thoughts how I can fix the 404 Page not found after installing the Contributions plugin? I tried everything, including accessing the .htaccess . And yes, user plugin was configured first.
This is what happens when I go to the page:

You mentioned this already but just to double-check, that the Contribution plugin is installed and active, you can go to its settings on the admin side?

Did you change in the Contribution settings the URL “slug” for the contribution page possibly?