Based on popularity and expanded functions, we would suggest that MetaTrader 4 (MT4) is a better platform than ActTrader. While ActTrader was founded in 2000, MetaTrader 4 is the worlds most popular trading platform, with over 14 million users worldwide as of 2014.
No, MetaTrader 4 is not a broker. MetaTrader 4 is a Trading Platform (software) that can be installed on a local computer. MetaTrader 4 (MT4) is predominantly used on Windows systems, or can be used on a Mac. MT4 is also available as a mobile app on both Apple IOS or on Android.
Retry logging into your MT4 account, it's possible you made a typo on your account number (username) or password.