Same issue as here:
https://forums.unrealengine.com/unreal-engine/unreal-studio/1617684-you-do-not-have-sufficient-permission-to-save-the-following-content-to-disk-4-22
I’m currently having to manually rename over 300 layer names which exceed the allowed length loading a Datasmith import from Revit. Some way for Datasmith to interpret longer file names from Revit would be good, manual method is in–practical with no ability to mass–rename within Unreal.
Unreal 4.22.1
I’ve had the same issue so here’s the answer I had from the support :
1 - enable long path support in windows using this tutorial >> https://eocloud.cloudferro.com/knowledgebase.php?action=displayarticle&id=135
2 - enable long path support in Unreal Engine in the “Editor preferences” menu.
3 - restart your computer, reopen the project and… voilà ! 
can we see what’s your situation? there’s some adjustments we could do in our exporter as well but we’ll need some details about what you are attempting to rename