I know the Screenshot is in libresprite not Unity but if you want to make your own TileSet - you need a few more tiles so that you have all the “angles” covered. There are some missing in the provided set - although I do get why since its free. (you dont need the 3 with the carpet since they are just for additional details and I have 2 bottom, 2 top, 2 side and 2 middle tiles which you can all cut down to 1 each but more varaety looks nicer…
Hope this helps^^