Every ArcGIS Online user receives a default 2000 credits in their Harvard account. We can allocate more credits to support your work if needed. When you run out of the initial default number of credits in your account, we add 5000 more for you without you asking. However, if you run out of that again, you will need to tell us how many more credits you still need to complete your work, before we can add more for you. The market value is 10c per credit. Fortunately, Harvard's site license with Esri allows us to pool our credits together for all users in the university, and most users don't need many credits, thus a small number of users can have many more without additional cost. But we want to use credits efficiently so not to run out of credits for the entire organization. Please go to https://doc.arcgis.com/en/arcgis-online/administer/credits.htm#ESRI_SECTION1_709121D2C7694DCAB9B8592F36F7A5BA to learn more about AGOL credits and how to estimate credit consumptions, and then let us know roughly how many more credits you still need, via https://gis.harvard.edu/contactus. We will add what you need to your account.