Copy script into /etc/profile.d/ directory using Wget:
sudo wget -q -O /etc/profile.d/motd.sh https://raw.githubusercontent.com/vangyyy/raspi-motd/master/motd.sh
sudo chmod +x /etc/profile.d/motd.sh
or with cURL:
sudo curl -s -o /etc/profile.d/motd.sh https://raw.githubusercontent.com/vangyyy/raspi-motd/master/motd.sh
sudo chmod +x /etc/profile.d/motd.sh
Optionally to remove the default MOTD run:
sudo truncate -s 0 /etc/motd