A test authorization for unomasuno.com.mx to the Let's Encrypt staging service has revealed issues that may prevent any certificate for this domain being issued.
Error creating new order :: Policy forbids issuing for name
The Registered Domain unomasuno.com.mx was found on the United States' OFAC Specially Designated Nationals and Blocked Persons (SDN) List. Let's Encrypt are unable to issue certificates for sanctioned entities. Search on https://sanctionssearch.ofac.treas.gov/ for futher details.