You could try
sudo mkdir /etc/pihole/
echo "release/v5.0" | sudo tee /etc/pihole/ftlbranch
sudo mkdir -p /var/www/html/admin
cd /var/www/html/admin
sudo git clone https://github.com/pi-hole/AdminLTE.git .
sudo git checkout release/v5.0
sudo mkdir -p /etc/.pihole
cd /etc/.pihole
sudo git clone https://github.com/pi-hole/pi-hole.git .
sudo git checkout release/v5.0
sudo ./automated\ install/basic-install.sh
However, this is untested.