MS Project 2013: How to create an Add-In (exe, dll)

Dear community,

I am a bit surprised that my last post somehow disappeared. Anyway I would still like to ask you for support on how to create an AddIn for MS Project.
I do have the code in VBA already and I created in the past already many Exel AddIns. Unfortunately I have no idea on how to create AddIns in MSP. I saw that you can select exe and DLL files and from my internet search I got the information that Visual Studio can create such files.
Not havining Visual Studio on my PC I wonder if there is any freeware (best portable) or any other solution on how to create an AddIn.

Thanks for your support.
Regards, Enze

Moderator bump