Contact the consulate of Mexico in your country and make sure if you require visa and/or vaccination card.
Compumag 2021 only issues letters of support for visa, once the author has registered and paid their registration fee.
Countries that require a visa to enter Mexico: here
Countries and regions that do not require a visa to enter Mexico: here
Links to Mexican Embassies and Consulates around the world where you can find out visa requirements, documents needed, make appointments for visas, etc. in different languages:
Mexican Embassies: here
Mexican Consulates: here