RE: Quick Campaigns Add Button Missing
Hi Murilo,
Yes, you can't create quick campaigns directly in the bar of the view, which is by-design.

A quick campaign is used to send a single activity to a list of contacts or accounts in your system. The activity could be an email, series of phone calls, letters, faxes or appointments. Quick campaigns are created from ‘Marketing Lists’ within the CRM.
Create quick campaign using in-app marketing-Sales Professional | Microsoft Docs
You can navigate to your Marketing Lists in siteMap, select the one you need, then 'Create Quick Campaign' button will appear in the bar.

Or you can open one marketing list you need, and then in the Quick Campaigns area, select New Quick Campaign

Or you can select records in the view of Account/Contact/Lead entity, click
button, then you can create 'Quick Campaign' for selected records.
Quick Campaign for Dynamics 365 Sales - YouTube
