Common LabVIEW file extensions are *.vi, *.ctl, *.lvlib, *.lvproj, *.llb.
https://labviewwiki.org/wiki/LabVIEW_File_Extensions has a complete list but I suspect your project is probably only made up of those 5.
The possible starting point would be locating any folder that has a lvproj file, as this is the extension for a LabVIEW project (since you have a built application, there should also have been a LabVIEW project).
You mention Simatic files, so it seems likely a Siemens PLC is used for data collection. Do you have any documentation (software/hardware) on the system architecture?
