Your thread asks two questions, so I will do my best to answer them both.
For the question stated in the title: For the Finnish version of the DAT Bootcamp, I would highly recommend going on the DAT Bootcamp website and contacting Ari to see if they have any alternate versions regarding the language. Keep in mind though, the DAT is administered in English, so I would just stick to the English version and not waste your time with the Finnish version.
For the question stated in the description: I finished it in 4-5 days and fully understood it after a week.