Code in this video_How to Install FreeOffice 2021 on Ubuntu Linux
sudo wget -qO - https://shop.softmaker.com/repo/linux-repo-public.key | sudo apt-key add -
sudo vim /etc/apt/sources.list.d/freeoffice.list
deb https://shop.softmaker.com/repo/apt stable non-free
sudo apt install softmaker-freeoffice-2021 -y