Spaces in library path names (on Windows) causes problems installing packages after installing R 3.5.0

[RuReady]

Then download package zip/tar.gz and choose install from package archive?

See also: R for Windows FAQ

If you want to be able to build packages from sources, we recommend that you choose an installation path not containing spaces. (Using a path with spaces in will probably work, but is little-tested.) Users of Vista/Windows 7/8/Server 2008/2012 installing for a single user using an account with administrator rights1 should consider installing into a non-system area (such as C:\R). Installing to a network share (a filepath starting with \machine...) is not supported: such paths will need to mapped to a network drive.