If the add-in is correctly installed, it adds a group to the Mailings tab of the ribbon.



Open your Letters merge document, ensure the Excel data source is attached and the document is saved. Click the Start Merge button in the add-in Group.

By default the template goes in the Word startup folder (with Word closed) If you have not changed the preferred startup folder it can be located (in English language versions of Windows) by typing
%appdata%\Microsoft\Word\Startup
in the Windows Explorer Address bar and pressing Enter.

This is all explained on the web page?

__________________
Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com

Thanks for all the help guys! The problem was indeed that the MailMergeManyToOne was not correctly installed. For some reason I couldn't get it to install with any of the files or methods described. So the toolbar I thought was from the ManyToOne was actually the Mailmerge tool in word. I used macropod's link, edited the macro a little and it works like a charm! Thank you very much sirs!