EU Schengen Visa- Does it Apply

I need to travel to Spain to implement a product for a few days. Does it fall under conducting business when i apply for a Schengen visa. can i just take a letter from my employer stating that i am implementing a product for a few days and they will process it


Below are the 4 categories

as a tourist
on business or to take part in a conference
to visit relatives and friends, or
simply when passing through in transit