if you are in Thailand longer than 3 months, the IDP isn't accepted as you are supposed to get a local license. That's all people are referring to. Valid real IDPs are accepted together with the home country license. IDPs can't be used alone without your home country's license.
That's a fake IDP, that's why it isn't valid. You probably got scammed by one of the many online websites offering IDPs. IDPs are only authorised to be issued by specific agencies for each country's license holders. For the USA, it's AAA, for the UK, it is the Post Office, etc.