Hello FuzzyTheWu, welcome to the Unreal community.
City Sample is quite in-depth and with that being said, the project is quite large. I would like to ask a few questions:
When you create a City Sample project, are you creating the project in your larger drive? I sometimes forget to change the default folder the projects want to create to when making a new project from the Launcher.
Are you interested in moving Unreal Engine to a new folder? If so, Ares9323 has some solid instructions along with PikaDERP who found a different solution.
I hope this helps