Add these file extensions into "allowedExtensions" lists for "Files" and "Documents" resource types in "/core/ckeditor/ckfinder/config.php" file:
docx,dotx,docm,dotm,xlsx,xltx,xlsm,xltm,xlam,xlsb,pptx,potx,ppsx,ppam,pptm,potm,ppsm
Add these file extensions into "allowedExtensions" lists for "Files" and "Documents" resource types in "/core/ckeditor/ckfinder/config.php" file:
docx,dotx,docm,dotm,xlsx,xltx,xlsm,xltm,xlam,xlsb,pptx,potx,ppsx,ppam,pptm,potm,ppsm