Right-click on the Toolbox and select Choose Items. Filter the list by OpenSpan.Office and you should find all of the connectors. Make sure they are all checked and they should appear on the Toolbox.
If you do not see OpenSpan.Office it would mean when you installed, the necessary files were not placed in the install folder. You can remedy this by looking inside of the install folder, finding the Office2016 folder and copying its contents to the root of the install folder.