The screenshot you posted is from the discontinued Plex for Windows and Windows Phone app, not Plex for Mac.
That app was last updated in May 2017 (announcement), discontinued in August 2019 (announcement), and no longer available in the Microsoft Windows Store.
Given the age of the client and the number of Plex Media Server updates since May 2017, there may be several features that no longer work.
Try the current desktop apps, Plex for Windows & Mac Desktop. Available at plex.tv/download.
