Airlines may allow the boarding of travelers who do not have this test, provided they state under oath that they were unable to take a test or obtain the result within the required timeframe. In these cases, the Colombian government may require testing and/or isolation upon arrival in Colombia.
Children under the age of 2 are exempt from presenting a COVID-19 test.
Travelers with proof of recovery from the virus within the last 90 days prior to boarding. Proof of a recent positive viral test and a letter from your healthcare provider or a public health official stating that you were cleared to travel.
More info at the CDC site
Travelers who did not get tested, are advised to stay home and self-quarantine for 10 days after travel.