I’ve seen lot many times people asking about the folder structure for weldment profiles in SOLIDWORKS. The folder structure for weldment profile is simply ABC.
A is the path for the folder that contains the Standard. For e.g. D:\Design Library\Weldments
B is the path for the folder that contains the Types. For e.g. D:\Design Library\Weldments\Inch
C is the path for the folder that contains the Sizes. For e.g. D:\Design Library\Weldments\Inch\10×20.SLDLFP
So when setting up the weldment profile location, you need to set the location of A under Tools > Options > System Options > File Locations > Weldment Profiles