GNU/Linux Fedora 34 Adding RPM Fusion Repo Guide
You are Welcome! The Tutorial shows you Step-by-Step How to Install RPM Fusion Repository in Fedora 34 GNU/Linux.
And to Enable RPM Fusion for Fedora 34 there are 2 procedures, but here I describe How to Enable it on the Fedora Command Line.
Finally, the RPM Fusion Repository for Fedora 34 includes both: Free Open-Source Software and Non-Free Proprietary Software.

1. Command Line QuickStart
Fedora GNU/Linux Terminal Tutorial for Beginners
2. Installing RPM Fusion Repo
First, Install RPM Fusion Free Repository
With:sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm
And then also the RPM Fusion Non-Free Repository
Like:sudo dnf install https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm
Authenticate with the User Admin Pass.
If Got “User is Not in Sudoers file” then see: How to Enable sudo.
Learn more on How to Setup GNOME Software & KDE Discover GUI on: RPM Fusion Official Documentation.
So Now I’m truly Happy if My Guide could Help you to Install RPM Fusion Repository on Fedora 34!