Make sure that folder exists. It should actually be trying to create that sub-compound file (.syscfg) here (note \Temp subfolder)
C:\Users\Public\Documents\Do-more\Designer2_8\Projects\Temp
Make sure you can create folders below
C:\Users\Public\Documents\Do-more\Designer2_8\Projects
specifically, the Temp folder.
Some PC Security tightens down folder settings - this is very rare, however - just in places with extremely secure PC admin stuff or strange virtual O/S settings, etc.