Hey Nagytalp,
first of all, thank you for the purchase!
In Ikebana, default WordPress-style blog posts and portfolio projects are different types of content. You’ve imported blog posts, are they are styled in a more blog-like classical layout (as in the theme demo here). In order to display the items are portfolio projects in a masonry layout, you would need to manually create the new projects (“Portfolio -> Add New” admin menu) and fill in the information from your existing posts. A more efficient solution, though, would be to use a third-party specialized plugin, e.g. this one.
You can read more about creating a masonry portfolio in Ikebana on pages 4-6 of the theme manual.
Should you have additional questions, do not hesitate to contact me!
Sincerely,
Andrii / Satori Studio