It is not about advertising. It is about licensing...
Viewing post in Pixel x16 Project version 1.4 comments
You need to open page of your asset pack (https://olteanugamestudio.itch.io/pixel-x16-project-version-02). In top of that you will see "Edit asset pack". You need to click it then you will need to to click step by step each of the following buttons "Metadata->Release Info->License for assets"... In the end you will need to select the license from the list