Whay does google says i have no structured data on my site? I thought this happened automatically in adobe muse?
One might assume why Google said so, if we could look at your site
Muse does not create any structured data. If you need it, then you need to do it manually. In the Google manuals, this is described in detail.
Is it important ta have a structured data?
This is just one small piece of SEO. The importance of this in itself is not too great, but it is an element of the whole puzzle, without which the overall picture will not be complete. However, without this your site may well exist. No one site has full picture SEO. The most important thing for a website is high-quality content. If there is no such content on the site, then structured data and other SEO trivia not will lead it to the top.