This is what I had to follow to get OSCOMMERCE to work on my UBUNTU Server 22.04 running a LAMP server!
On the Splpah window everything would show up and all work except for the ADMIN page.
Whenever I clicked on or even entered the ADMIN into the address bar it would always throw a 404 error.
Make sure that you Enable .htaccess on Apache 2 Linux Server
you can find the directions at the link shown below and now everything even ADMIN LOGIN appears to be working correctly!
https://linuxconfig.org/enable-htaccess-on-apache-2-linux-server