Lets Encrypt and WP Multisite

Hi

I have activated my Lets Encrypt on my WP Multisite and after that, I have installed the Plugin Really Simple SSL and when to activate that plugin, show a message saying I don't have SSL.

I have read this blog post https://premium.wpmudev.org/blog/ssl-domain-mapping/ but I don't have sure if I understand very good.

If I go to my Domain Mapping Plugin and when say "Force http/https (Only for original domain)" if I activate both for force https, the SSL will go work?