Laravel is recommended to be used with a VPN, where you have full control over your server.
All I can think of is that you don't have enough permissions to create a symbolic link on that shared server.
I take it that at the moment your using the local disk in the storage options.
I think you might be able to get it working using Amazon S3 or similar because you would not be required to create the symbolic link to access the files in your /public/storage directory.
because i separated the public folder and rename, i just copy the content of public and move to public_html, where another laravel file is store in ..outside public_html @Snapey
You asked how to create symlink. Your hosting provider won't let you. I suggest you write the files that you would have put in the symlink folder, instead direct in the public area of the site so that a symlink is not required.