Hello,
I don't believe Version 2 has been available to install in a few years; if the other users have installed within the past few years they should have Version 3.
When the other users try to run the merge I would recommend they be logged into only one Google account or be in a Chrome Incognito browser. This file you shared with them should originate on your Drive. Autocrat does not work correctly if the file is placed on a Team or Shared Drive. Another thing to note if they are still having issues is to ask if they have add-blockers or web-filtering software installed which can sometimes prevent add-ons from functioning. Other than that they should be able to run the merge you created from the Autocrat module.
Thanks!