In short: I developed that map for almost 3 weeks to sell it later. When I have done that, the shop said that I cannot use models with my actual files format so I had to create the map from the beggining. I was little confusing but I did not give up. After next 2 weeks I have done it again and I realised that I swapped old files with the same as before. So I created the same map using the same format of files - again. I was really tired and after a little break I came back to home and I started to make that map for the third time. Finally... Unity Assetstore didn't want the project but that was a huge lesson for me... Now I am checking everything twice and I know that if I want to create something... nothing can stop me.