NPM unable to find a file at installation

[concAPPtLab]

I am trying to install KeystoneJS on Windows 10 64-Bit. Installed NodeJS and MongoDB (MongoDB Server runs). Wanted to install KeystoneJS in the separate folder C:\KeystoneJS. Executed npm init, npm install -g yo -S and npm install -g generator-keystone -S from that directory. The installation of Generator-Keystone fails though. This is the whole output:

C:\KeystoneJS>npm install -g generator-keystone -S
npm WARN deprecated CSSselect@0.4.1: the module is now available as 'css-select'
npm WARN deprecated CSSwhat@0.4.7: the module is now available as 'css-what'
npm WARN deprecated simple-bufferstream@0.0.4: no longer maintained
npm WARN deprecated minimatch@2.0.10: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue
npm WARN deprecated minimatch@0.3.0: Please update to minimatch 3.0.2 or higher to avoid a RegExp DoS issue
npm ERR! path C:\Users\<My-Username>\AppData\Roaming\npm\node_modules\generator-keystone\node_modules\readline2\node_modules\strip-ansi\cli.js
npm ERR! code ENOENT
npm ERR! errno -4058
npm ERR! syscall chmod
npm ERR! enoent ENOENT: no such file or directory, chmod 'C:\Users\<My-Username>\AppData\Roaming\npm\node_modules\generator-keystone\node_modules\readline2\node_modules\strip-ansi\cli.js'
npm ERR! enoent This is related to npm not being able to find a file.
npm ERR! enoent

npm ERR! A complete log of this run can be found in:
npm ERR!     C:\Users\<My-Username>\AppData\Roaming\npm-cache\_logs\2018-07-09T11_55_10_518Z-debug.log

C:\KeystoneJS>

Can anyone help me out?