Ok I’ve amended my original instructions. It will be quicker if you start from fresh instead of trying to manually edit what you have so far particularly if you’re not very familiar with Linux. Just follow these instructions and please let us know it’s working this way.
sudo apt install apt-transport-https dirmngr gnupg ca-certificates
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 3FA7E0328081BFF6A14DA29AA6A19B38D3D831EF
echo "deb https://download.mono-project.com/repo/debian stable-raspbianbuster main" | sudo tee /etc/apt/sources.list.d/mono-official-stable.list
sudo apt update
wget https://github.com/genielabs/HomeGenie/releases/download/v1.3-stable.19/homegenie_1.3-stable.19_all.deb
sudo apt-get update
sudo apt-get install gdebi-core
sudo gdebi homegenie_1.3-stable.19_all.deb