So basically only thing I have is wallet.dat folder without seed or password
Without seed you have only the watch only wallet. You can not spend the coin. There are people online most likely scammers, they sell wallet files in exchange of bitcoin I don't know how lucrative the business is but may be it works to trick people and they make money from it or we would not see them to invest their time in it.
How did you get the file?
Yeah sorry my bad its not wallet.dat its just default_wallet file here is the picture:
https://ibb.co/sQQhC6y