Mid 2009 MacBook pro cannot download osx
As you have the Snow Leopard disk, you can use another mac with an optical drive to create a bootable USB installer by following the answer to this question How to create a bootable OS X Snow Leopard USB drive? and using the Snow Leopard install disc instead of the iso file that is mentioned in the answer.
If you don't have another mac with an optical drive, you can either use the Snow Leopard install disc in a PC with optical drive to create an iso image, or download an existing iso image by following this answer: macOS won&#39;t boot into Recovery mode, need to reset admin password, and use it in the process outlined in the answer linked in the first paragraph to create a bootable USB installer.
Plug the bootable USB media into the 2009 Mac, reboot it while holding down the option key and select the USB device.