Downvoted, but correct.

https://www.federalreserve.gov/faqs/currency_12772.htm

There is no federal statute mandating that a private business, a person, or an organization must accept currency or coins as payment for goods or services. Private businesses are free to develop their own policies on whether to accept cash unless there is a state law that says otherwise.

Only debts. Receiving a good/service might generate a debt, but not always; for example, if you pay in advance for a service.