Based on that crash and the fact this is done in a UMG blueprint I speculate you didn’t add the zip utility interface to the Mods_Widget1 calling this function see this section: https://github.com/getnamo/ziputilit…ueprint-access for details on usage.
NB: Thanks for spotting a crash! It’s bad design for the plugin to crash when the interface isn’t set, so I added an issue to change the crash to a warning here: Add graceful warning instead of crash when called from e.g. a UMG blueprint with no delegate · Issue #32 · getnamo/ZipUtility-Unreal · GitHub. It may be a long time before I add the enhancement though.