You will need to enable Salesforce campaign sync first.
When syncing an SFDC campaign with a Marketo program, the implied SFDC actions (e.g., add to SFDC Campaign, Sync to SFDC) will be disabled for child campaigns of the program.
1. Go to Marketing Activities.
2. Select your program.
3. Click Program Actions, then select Salesforce Campaign Sync.
4. Select Create New or choose an existing Salesforce campaign.
If you select an existing Salesforce campaign, make sure to match the program statuses of the Salesforce campaign and the Marketo program.
5. Enter a name for the new campaign and click Save.
6. Now you can verify the campaign sync details in the program summary page.
Excellent! Now any program status changes in Marketo are synced to the SFDC campaign and vice versa.