If they are truly a non-profit (relevant Govt documents), I'd go this way ...
- Tableau Foundation for free (depending on country) copies of Tableau Desktop
- Alteryx For Good for free copies of Alteryx Designer
- Snowflake for database. There is NO free option here, but there are ways to reduce the costs as much as possible.
Snowflake does all the storage
Alteryx does all the data prep/staging/pre-calc's/etc
Tableau works just as it did before.
I'm assuming you're USA based, but I'd be happy to assist on this project. You can contact me directly (details on my profile) if you want to discuss further in private, or post here as well