Hi - when a program is synced to an SFDC Campaign, all the leads that are members of the program and have been given statuses will sync to the Salesforce campaign automatically. The flow steps associated with SFDC campaign sync no longer function (they are what Marketo call "implied sync actions" that will occur automtically because the program is assocaited with the SFDC campaign).
This message is simply telling you that Marketo has skipped that flow step because it is redundant. Check the Summary screen of your program, you'll see the program is synced to a campaign at that level.
If I was to hazard a guess as to why your leads aren't syncing to the SFDC campaign even though your program is associated to the campaign, you may not be correctly assigning Program Statuses to your leads as they come into the program, so they won't sync to the Salesforce Campaign with the correct campaign status. Check that you are using the Change Program Status flow step to assign new leads through the form the appropriate status.