Did you follow the instructions at https://rpmfusion.org/Configuration before you did anything else? That would have set up the rpmfusion repos so you could install the drivers. I checked and although your card (GTX 660) is old it is still supported by the latest drivers according to nvidia.
Once that was done then a simple dnf command would install the rest.
sudo dnf install akmod-nvidia nvidia*455* kernel-devel kernel-headers xorg-x11-drv-nvidia*455*
That is the command I use with a new install to enable and configure the nvidia drivers. It downloads the packages and installs them and after the install is done the akmod-nvidia package builds the kernel modules for the driver. My command differs from that in step 4 of the instructions you posted with the link, but is more comprehensive. If you used the instructions from your post from us.download.nvidia.com ( Chapter 4. Installing the NVIDIA Driver) then it is likely there is an error because those are the raw drivers and the ones from rpmfusion are the ones that have already been tweaked for fedora.
If not all that is installed then the drivers may fail. If installed from some other repo they might not be tweaked to work with fedora and require some tweaking by you to work correctly.
If you already have done the install then in order to make certain that everything is clean and coincident I suggest you remove all installed nvidia packages with the below command and reinstall with my command above.
sudo dnf erase '*nvidia*'