You can build the module with DKMS like this:
sudo dnf install git-core dkms kernel-devel openssl
sudo git clone https://github.com/umlaeute/v4l2loopback.git \
/usr/src/v4l2loopback-git
sudo dkms add v4l2loopback/git
sudo systemctl restart dkms.service
sudo tee /etc/modules-load.d/v4l2loopback.conf << EOF > /dev/null
v4l2loopback
EOF
sudo systemctl restart systemd-modules-load.service
If using Secure Boot, enroll the relevant cert:
MOK_PASS="fedora"
sudo mokutil -i /var/lib/dkms/mok.pub << EOI
${MOK_PASS}
${MOK_PASS}
EOI
sudo systemctl reboot