After you have added the List into Power BI use Power Query Editor (the ellipses on the table and then select edit query) and find the column in question.
As you see below there is a MemberId Column in my example which contains a List value.
Select the Double Arrows and then select Expand to New Rows.
You should see a result where each member of the group gets their own row in the table.
It will come out with the User ID but you should be able to link this the same as you did with point 1.