You need an embassy visa for Namibia if you have a Mexican passport
Visa options for Namibia
Electronic visa on arrival for Tourism
Travelers need a visa to visit Namibia for Tourism. A Namibian Electronic Visa on Arrival is the fastest and easiest way of obtaining a visa for Namibia because travelers can submit their application and supporting documents online. Once the application is approved, travelers receive their eVisa confirmation electronically.
This is not offered by sherpa°.
Apply on the government site.