Seems like it doesn't like question marks in the file path. What is the output of calling .libPaths() for you?
.libPaths()
Try creating a directory somewhere locally that you have write permission like C:\Users\jimmy\rlibrary and then setting that as the .libPath in R using
.libPaths("C:\Users\jimmy\rlibrary")
After then, when you're installing packages using the dialog Tools>Install Packages.. make sure that the "Install to Library:" option matches the directory you created.
If that allows you to install packages, you'll have to setup that directory as your default library path. You can do this by creating a .Rprofile file in your home directory and adding the libPaths("path\to\your\lib") command into it so it gets run when Rstudio starts.