I am also having this same issue, although I am using 10.4.1. Instead of a screenshot i just listed the text in the error message below.
Error: GeodatabaseDiagrammer.ViosoDiagram.OpenVisionDrawing(StraingfileName, String pathName) at GeodatabaseDiagrammer.ViosoDiagram.StartDiagram(String cPathName, String strVisioOutputFile) in C:\Temp\StudioAT\ArcGIS\RepositoryGitHub\GDBDiagrammer\SourceCode\Helpers\VisioDiagram.vb:line80 Msg: Could not load file or assembly 'Microsoft.Office.Interop.Visio, Version=15.0.0.0, Culter=neutral, PublicKey Token=71e9bce111e9429c' or one of its dependencies. The system cannot find the file specified.
I love this tool and have relied on it for may years to discuss detailed GIS layer design options with non-GIS or non-technical staff. I have just upgraded my ArcGIS desktop to 10.4.1 Geodatabase Diagrammer version from github, and I have Visio Standard 2010. I have downloaded the 10.4.1 version. I have moved the stencils to the proper location and ensured that the paths are pointing to these locations, however I am still getting an error and am not sure what I am missing. I have also opened the templates and resaved them if prompted to the current version of Visio. Please help, as I love this tool! Thanks in advance.