Spirit Airlines website states 5 days and is a tad misleading (Rapid Antigen) but probably should be printed as evidence

Quote
Spirit Flight Schedule: Spirit has resumed service and is currently operating all scheduled flights to St. Maarten. Book now.

Testing: All travelers are required to provide a negative COVID-19 PCR or Rapid Antigen test result, which has been taken within 5 days of travel.
Quarantine: There are currently no requirements for quarantine.