You can download the list of users who are in a live experiment by control and variant. This is done by going to the User's Tab that lists all users by ID. Note that your experiment must be active in order to access and export these results.
Step 1: Apply the filter of the specific experiment and search. This will return all users who have taken part in the test.
Step 2: Download the CSV.
Please contact firstname.lastname@example.org with any questions.