Linux Ubuntu 18.04
cd ~/Downloads
wget http://packages.elementary.io/appcenter/pool/main/c/com.github.alecaddd.sequeler/com.github.alecaddd.sequeler_0.5.5_amd64.deb
sudo dpkg -i com.github.alecaddd.sequeler_0.5.5_amd64.deb
sudo apt-get install com.github.alecaddd.sequeler
Please let me know in the comments if this helped you out or if you feel there should be extra steps.
Thanks! Works like a charm on Ubuntu 18.04.1 LTS