Please ensure you have updated to Astute Manager v2 before proceeding. An easy way to tell the difference is that v2 operates in a larger window, whilst v1 was constrained to a smaller, vertical window locked to the top right of the screen.
If you wish to install a single plugin (including a new release) please follow these instructions.
Quit Adobe Illustrator
Load the Astute Manager and sign-in as instructed
Ensure you are managing plugins for the intended version of Adobe Illustrator (you can only manage a single instance of Illustrator at once):
4. Click on the Install button associated with the intended plugin: