Installing new software

I'm new to Linux (Ubuntu MATE 20.04). I have opened the Software Boutique and clicked Install for Calibre which now shows Queued for installation but cannot see how to proceed from that point!

if you click on the green button, apply changes, it should install.

Hello @teal

First, select the bulk queue button


You will then be taken to a page showing all your queued selections. Just select Apply Changes

Your Software Boutique is likely green as @pavlos_kairis typed. I've played about with my theme.