Hi, this is a specific tileset for use with the RPGMaker MV game engine, as specified in the title and description. This is due to the fact that the tile sizes are 48x48px, but are designed to look like 8x8px tiles.
If using in Unity, you may have been better using the actual 8x8 tileset I have for sale; But I have not tested it in Unity (I use GBStudio!)
I think to get a refund you can talk to itch, but it can take some time to get that refund, so instead, would you like me to send the 8x8 tileset to the email address you used to buy this tile set? Free of charge - I feel this was a genuine mistake, and I would like to give you the other assets so you can try them, and hopefully start making your game :)