Hi, I just installed the plugin, and for the moment seems to work fine ! I wanted to ask you if I could translate it to spanish, and how. Thanks

If you are talking about the front-end, you can easily override the component partials. More information about this can be found here: https://octobercms.com/docs/cms/components#overriding-partials

If you are wondering why error messages are in Dutch, it's because we believe that every application calls for its own style of messages. It serves as a placeholder for your own messages.

For further assistance please feel free to ask!