Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello
The only free license is Microsoft 365 Business Basic, however, it doesn't come with desktop version of the Office apps. You would have to use web based via www.office.com. You still have the Exchange email account, you still have Teams and OneDrive.
Otherwise, in your Admin Center https://admin.microsoft.com, Look under Billing > Purchase products, search for Microsoft 365 Business Standard, make sure you view it in the Nonprofit tab, it will show you the discounted price. That one is a bit cheaper than premium, and it should also come with discount. And it has the desktop version for the apps.