Please install a clean Wordpress anywhere, it could be in a sub-domain or sub-folder and that will be your staging. Your hosting provider should have a way to install it automatically, like the script installer of CPanel. Then follow these :
- Install All in one migration plugin on both your live site and staging site
- Export your live site as a file using the migration plugin
- Import the exported file to your staging using the same plugin
That should create a staging. There are many possible ways and maybe your host has better feature for creating staging.
Yes, I understand and I too will be more cautious. I personally prefer having multiple instances of staging when working for versioning. Anything could happen
Then please provide the FTP login credentials in your staging. I'll try finding what's causing this.