Zotero 6 was released on March 17, 2022, and contains many helpful updates, including annotations and notes features and an iOS app. More details can be found on the Zotero blog.

The PDF reader is now integrated into the Zotero program, in a different tab than where your library is (1). You can color-code your annotations (2) and see them all on the left-hand side of the screen (3). You can also take notes on your annotations (4). You can also add an item note from the annotations (5).