IBPlugin is now freely available, but not as open source, as the sources are still used in numerous projects.
IBPlugin can only be used under Windows. It is a general plugin that provides large parts of the InteractiveBrokers API quite comfortably.
IBPlugin is now license-free for users. It can be downloaded here.
Questions will be answered on our Discord Channel ibplugin.
In these playlists you will find videos on how to use IBPlugin in Multicharts (TradeStation) and MetaTrader.
If you need more help, please buy support.