Download using the GitHub .zip download option and extract the .zip file to the themes directory i.e. /usr/share/themes/ or ~/.themes/ (create it if necessary).
To activate the theme in Gnome, run the following commands in Terminal:
gsettings set org.gnome.desktop.interface gtk-theme "Dracula"
gsettings set org.gnome.desktop.wm.preferences theme "Dracula"
or Change via distribution specific tweak tool.
INSTALL.md is derived from Dracula GTK INSTALL.md