I read on https://www.aviacioncivil.gob.ec/que-debemos-saber-antes-durante-y-despues-de-un-viaje-en-tiempos-de-covid-19/ (mirror) (translated to English by Google):
Travelers will be asked for a negative result of a PCR test, performed up to 7 days before the trip. In the event that the PCR test cannot be performed in the country of origin, the passenger, upon arrival in Ecuador, will undergo the test to detect SARS-CoV-2.
Non-resident foreigners will carry out their APO (Obligatory Preventive Isolation) in temporary accommodation.
Are temporary accommodations where non-resident foreigners carry out their APO (Obligatory Preventive Isolation) designated by the Ecuadorian authorities, or can the non-resident foreigners choose them themselves (e.g., renting Airbnb)?