A VSTO is an Office 365 document coded in C# that functions as an automated template. When opened, it creates a new instance by running the initialisation events and subsequently controls user interaction. In Trade Control there are two:
Download the templates from the latest office client release - tcOfficeTemplates.zip and tcOfficeCashFlow.zip.
The VSTO Excel P&L and Balance Sheet should automatically request installation when opened for the first time, or just run setup.exe.
To the right of the spread sheet is an Action Pane. Upon first use, specify the server name (e.g. tradecontrol.database.windows.net), the authentication mode and credentials. If the connection is successful, save the document so you will only need to enter your password next time around.
When you open templates for the first time, like the P&L, they should automatically request installation. Alternatively run the setup.exe directly.