The sidebar isn’t a plugin, it’s part of the core of Discourse.
These are all configurable via /admin/site_settings - search for sidebar to see them
If you’re referring to the location to customize the contents of the subscriptions banner, this is done via your Customize → Text at /admin/customize/site_texts by modifying js.discourse_subscriptions.campaign.title and js.discourse_subscriptions.campaign.body.
I’m wondering if @Giovanni_Lignarolo had indeed done this search and was listing what was displayed in order to learn what the ideal (“correct”) configuration is for each option? Sometimes as an Admin, I don’t really understand what the full impact of the settings I select will be, even with the explanation that shows up under each field.
Is there a guide to the configuration? (I couldn’t find one, but probably missed it!)
@Giovanni_Lignarolo, I don’t think there’s any one specific “correct” way to configure the sidebar - it’s going to depend on how you want to use it. Is there something in particular you want to enable or disable about the sidebar?