iOS Activation vs Plex Pass

I am trying to used a shared Plex server on my iPhone. When I open the Plex app, it will not let me stream more than a minute without a one-time activation or a Plex Pass subscription. What is the difference between the activation and the Plex Pass subscription? I cannot find anything on the website differentiating the two. (I understand the worst-case scenario is to stream through an internet browser).

One time activation means ($4.99, i think?) Plex app only for IOS for any compatible ios device that uses your Apple login.
PlexPass monthly, yearly, or lifetime subscription means Plex apps for any device Plex supports, and, so much more.