Why can’t you use it in a donut chart ? if you use the measure as a value, you can add “userID” as a group/color. If you want to use the measure as the group/color, I think you need to do it in the dataset
Here is how it might look for your use case. You don’t have to make a count_distinct calculated field. You just need to add the usage_date as the value and take the count distinct value of it.