Webcouturier.dropdownmenu is not showing in add-ons

Hi, I m new to Plone. I am using Plone5.0.4

i added sources.cfg in plone folder.
sources.cfg :
[buildout]
extends = http://plonesource.org/sources.cfg
extensions = mr.developer
eggs +=
webcouturier.dropdownmenu
auto-checkout =
webcouturier.dropdownmenu
[sources]
webcouturier.dropdownmenu =
git https://github.com/collective/webcouturier.dropdownmenu.git
zcml =
git https://github.com/collective/webcouturier.dropdownmenu.git

Then added sources.cfg in buildout.cfg file
[buildout]
extends +=
sources.cfg

After that i run the below commands.
./bin/buildout -N
./bin/instance fg

then successfully created webcouturier.dropdownmenu folder in ./src folder. Server also running properly.

But the add-on is not displaying to activate in site setup -> add-ons.

Please provide the proper solution.