Problem downloading extensions

Hi all! I am having some problems downloading the extensions. I have installed 4.10.2 version for MAC. The extension manager does not work, and i do not understand the reason.
I want to make a registration in brain IMR, do you recommend some modules?
Thank you!

It could be a proxy issue and maybe you need to manually install. Discussion below should help.

Thank you very much for your useful answer!!

Have you found the solution?

Maybe you have not installed Slicer - see information here: Slicer app installation "hint" for mac installer