Error message "Update Failed: Could not create directory."
If you see this error using one of ShortPixel's plugins, it is related to file permissions and ownership and usually occurs after a website was moved from one hosting provider to another. You may want to check here for more info.
Fixing the file permissions/ownership to match those of the webserver is usually something that your hosting provider is best fitted to help you with. Please contact them and let them know about this issue.