You need a subscription to a TV provider like Spectrum or Cox Cable. Or if you have a subscription with Hulu, the package with Disney+, Hulu and ESPN Unlimited will give you access to SECN and SECN+ ( https://www.hulu.com/disney-hulu-espn-unlimited-bundle?from=welcome).

Another option - I have a YouTube TV account and have access to several ESPN channels, including SECN. It does not give me access to anything on ESPN+/SEC+/ACC+. 

ESPN+ gives access to SEC and ACC including the plus versions from what I can tell, though would not call myself an expert at figuring this stuff out. 

Family nudists 

@melissa-jm we have YouTube tv also. If you sign in to the eapn app with your YouTube tv login, you can stream sec+ and acc+. Not as user friendly if you want to stop and rewatch specific things but better than not having access at all.