I don't know any information about the site you provided.
But I have been dealing with counterfeit money for a long time and have a lot of experience using it.
The main thing is to avoid ATMs and any machine checks. Also, do not allow bills to fall into adding machines.
No matter how good a fake is, it is a fake, not an original.
Do not take them to banks or official exchange offices.
Look for those who exchange illegally.
Better yet, just buy something and take the change.
Good luck. I hope I helped.