Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hi MarcVan,
Do you mean that you want to let 4 users use Office 365 ProPlus and 30 users use Outlook Web App via browser? If so, you can assign Office 365 ProPlus license (E3) to the 4 users and Exchange Online license (E1/E3) to the rest 30 users.
Regards,
Ryan