Solved Cannot play getting this error

Looks like the *.dll library file required to run the game is corrupted, try reinstalling the server patch again and make sure you select the game folder.
If that doesn't work follow this post, install the game in C:\ or a different partition if you have one and make sure the TDAgg3.dll file mentioned in the error message is not deleted by your antivirus or windows defender and it's fully copied to your diablo game folder upon installing our server patch. Also I wouldn't recommend choosing desktop as your install folder for any applications since folders like users/desktop/documents, etc are usually protected and have limited permissions.

LE: I see you were already able to connect to the server before my reply so did you fix it?