If you are using AutoCAD 2010, as you state in your private message then you are somewhat limited in how you can run that add-in. 2010 predates the .bundle structure so you will have to run the code via AutoCAD's Netload command.
Sequence of events:
Download the attached, and UnBlock the zip file.
Place the file, STSC_Text2Geom_v18, into the folder where the Acad.exe file resides. Usually in the C: - Program Files - …
In AutoCAD, use the NETLOAD command and navigate to that file location. Or