The Mini-app tab gives access to all of the published Mini-apps in a workspace. Shown as tiles in a gallery format, Mini-app can be run directly from this tab by clicking the 'Run' button in each. 
Understanding the Mini-app tiles
Each Mini-app tile shows the status of that Mini-app at the current time. The status is shown in the sidebar as well as on the tile.
A red dot and the word Stopped means that the Mini-app is not running in the workspace. To start the Mini-app, click 'Start App' or anywhere on the tile.
A green dot beside the word running means the Mini-app has been started and may be in use by another user in the workspace. To start your own session of the Mini-app, click 'Connect' or anywhere on the Mini-app tile. The status and R image which the Mini-app is running on are shown on the right-hand sidebar along with the name of the user who started the Mini-app.