Here's a link of Labs all over Costa Rica that perform COVID tests in case someone isn't staying at one of the hotels in the Gulch.
https://ticotimes.net/wp-content/upload ... e-2021.pdf It has the addresses of the Labs and best of all, at lot of the labs have a WhatsApp number so you can contact them directly with any questions. In my case I was living in Barrio Escalante, 3 days before I was due to leave I texted La Paez Laboratory in Los Yoses and asked if they performed the COVID test and what type-PCR or Antigen? Anyway, they texted me back a brief form that I needed to fill out (name, address in CR, dates of travel, etc.) on their web page and told me that no appointment was needed just that COVID tests were performed daily between 10am-noon and 2pm-4pm. I showed up the next day around 10 am, they already had my info from the form filled out, I waiting about 5 minutes, then i got the antigen test which took about 3 mins and about 3 hours later received my results back via e-mail. I couldn't believe how smoothly everything went, which if you have lived here before, you know nothing ever seems to go smoothly-LOL.