Ask about not-for-profit pricing explicitly
Concessional arrangements for registered charities do exist at several levels of the payments chain. They are not usually part of a standard quote, and nobody volunteers them.
If you have registered status, it should be on the table before you sign anything. The worst outcome of asking is a no.
Recurring giving is a different product
A regular monthly donation is a stored-credential transaction, priced and handled differently from a one-off tap. Expiring cards and failed rebills are the quiet source of attrition in a regular giving program.
How a provider handles a declined recurring payment — whether it retries, and whether it tells you — matters more to your income than a small rate difference.
Donation terminals and events
Fixed-amount tap points and event terminals are usually needed in bursts rather than year round. Short-term or seasonal arrangements exist and are worth asking for rather than carrying a full year of rental for a few weeks of use.