You have a lot of research to do -- and nobody on this forum can do it for you, since it is specific to your site. You need to find out who is responsible for the AS/400, then find out how the AS/400 is networked, then determine what type of processing you can do on the AS/400 to automate what you want automated. You may need to use FTP, you may be able to use a shared drive, you may have to use REXEC to start a process on the AS/400. Which will you need? Only somebody responsible for the AS/400 and working at your site can tell you which, if any, of these options could be used -- and which should be used.
Sometimes a forum can be a help, and sometimes it cannot. In your case, for what you want, there's no way a forum can provide you assistance. If you need more help than you're getting internally, you need to convince your management to hire a consultant to assist with the set up.