Metabase is a way for you to ask questions of data that is in a database. In general, we expect that you BringYourOwnDatabase. We have one exception to this (Google Analytics), but in general, we don't support "cloud services" so much as Databases or Data Warehouses that might or might not be in the cloud.
If you want to try out Metabase, you can play around with out sample data set or download data sets in SQLite format. If you want to go deeper, try installing MySQL or PostgreSQL and import your data into those.
We don't support direct import from Excel sheets for the time being.