It is not as easy to share an entire solution as it used to be to share a VBA template or a VB 6 project
VB solutions have solution and project files with file paths specific to a developer's machine. The solution file is found at the root of the folder with an .sln extension. The project file is at the same level as the source code and has a vbproj.user extension
The vbproj.user file specifies the path of the application to be used for debugging. In our case, this is ArcMap. You can change the path name to match the location of your local ArcMap installation. In the example attached I used the environment variable AGSDESKTOPJAVA to point to my local installation
You will also need to remove and re-add all of the ESRI references to the solution if your ArcMap SDK is installed at a different location
Given all of this, it may make sense to create your own solution and add the source files created by others
Follow the steps 1-6 here to create an ArcGIS Visual Basic project
Next copy all of the .vb and .resx files from the incoming project root to your project root. There may be additional folders containing project code depending on the structure of the project. And you'll need the Config.esriaddinx add-in configuration file. Overwrite the new file that was generated when your project was created with this file.
Use the Add Existing Item functionality in Visual Studio to add each item to your project
More research required on sharing code via Visual Basic templates (link)