The Useful Plugins section contains some nice to discover plugins that are guaranteed to work great with Blocksy. Though, on some very specific setups, the “Install” buttons might be missing from view, making installation of these plugins “impossible” (not really, but we’ll get to it).
This is a very common occurrence with overprotective “security” plugins that might block the installation of other plugins if it’s not done via the main “Plugins” section of the WordPress Dashboard. It is not something to be scared of as the “issue” can be fixed quite easily.
First, you might try temporarily disabling all security plugins to see if this allows the installation of third party plugins from other places. If this works, you’re golden. Alternatively, you simply need to copy and paste the name of the plugin and search for it in the “Plugins” page of your WordPress Dashboard, then install them as you would with any other plugin.