The main thing you'll need is a calendar for your entire date range that isn't connected to your data. So for example if your earliest start date is 1/1/2016 and your last date is 6/21/2020 - you'll need a daily calendar for that entire range.
Once that is in place you can just use that Date as the dimension and the following expression as the measure =SUM( Aggr( IF(Date >= [StartDate] and Date <= [EndDate], 1,0),Date,ID)). This uses the AGGR function to aggregate on the calendar date field and ID with a conditional if statement where it does the validation if the ID was valid during the time period. If so it returns 1 and is summed for that day.
You will need to check your edge cases for missing start dates/end dates. If this can occur you can either fix it in the backend script or use OR/ISNull statements to manage these cases.