Sass Compiling Error

app.css
"File Permissions Error, could not write to the CSS directory."

admin.css
"File Permissions Error, could not write to the CSS directory."

app_variables.css
"File Permissions Error, could not write to the CSS directory."

app_hamburger.css
"File Permissions Error, could not write to the CSS directory."

app_fonts.css
"File Permissions Error, could not write to the CSS directory."

app_normalize.css
"File Permissions Error, could not write to the CSS directory."

app_tools.css
"File Permissions Error, could not write to the CSS directory."