Hello,

i cannot install any extensions modules.
I am using Modelio The Open Source modeling environment Version: 2.2.0

The menu items under -Extensons- are grayed out.

Hello,

In Modelio, extensions modules are project specific, meaning that for example an extension like JavaDesigner can be "installed" in your development project but not in your analysis project.
The consequence is that to install a module, you first have to (create and) open the project you want to install the module in, in my example your development project.

See these quick instructions on how to create a project.

Edit: the following pages of the user manual contain more detailed information on project creation and opening:
Creating a Project in Modelio
Opening a Project in Modelio
and this page contains detailed information about Modules in Modelio:
Working with modules in Modelio