Correct contact information:

Professor Matti Mäntysalo
tel. +358 40 757 6800
matti.mantysalo@tuni.fi

Project Manager Markus Tuomikoski
tel. +358 40 730 9084
markus.tuomikoski@vtt.fi

I paid extra for top designers. I have not limited participants in purpose..

Thank you very much for your answer.
But to my great regret, your project really has limitations for the participation of designers. That is why I don’t see the "submit your design" button in your project. With other similar projects, I had no such difficulty.
Here is the technical support answer to my question:
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Tech support:
Only designers with 2.5 rating on the brochure design category and able to participate in that contest because it's a MiniCrowd.
...
For now, look for unlimited designers projects since it has no restrictions on the ranking.
If the project says that it's a MiniCrowd or MiniContest, it's possible that you will not be able to participate since it requires a 2.5 rating. You will be able to increase your ranking by participating in unlimited designers projects.
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Perhaps this will somehow help to understand this problem as well as the fact that it really exists. Since it took several days to find out this strange problem, I probably will not have time to take part, even if you remove the restrictions.

Thank you!