This marketplace has an offer-based structure, meaning that one buyer can see multiple offers from different sellers for the same product. 

It is then very important that you follow our recommendations in this guide to create effective offers and boost your position on the offer listing.

All the data in your catalog must be sent in Polish (titles, description, etc.) to display on this marketplace.  

Please check Allegro documentation if you are EU company or NON-EU company to register and activate your account.   
Allegro now requires that for some categories you have a minimum % of your offers assigned to an existing product on the marketplace.
If you do not meet this condition, you might be unable to list new offers in those categories.

Details of the concerned categories is here!