Advertising and marketing agency seeks project management software

We are a small advertising and marketing agency with clients primarily in the IT, technology, and industrial sectors, and we are looking for project management software that meets the following criteria:

• Documentation of project information
• Archiving of correspondence, e.g., emails (from MS Outlook), phone call and meeting minutes
• Exchange of work instructions, e.g., notes, comments, and reminders
• Calendar function
• Definition of project timelines with automatic time adjustment
• Support for operational project work
• File export
• Creation of (post-)calculations
• Billing
• Time tracking
• Job tickets for direct customer involvement
• Usability via mobile devices through responsive design or an app
• Access from various workstations: agency, home office, mobile while on business trips
• Possibly web-based
• German version available
• Direct customer service for questions regarding the software

At least 6 software workstations are planned, with the possibility of more later.