SUMIFS for Date Range

here's the basis of my struggles boiled down:

Facts:
I have 5 buildings, each with 100 rooms.
Groups of people enter come and go from different buildings
Groups range in size from 10-100 people
Each group has a specific Entrance and Exit Date

Needed:
determine is a building is in use based on a 'Start Date' column, 'End Date' column, and a reference date
count the occupancy of the room on a day a building is in use


Attached is what I have so far.

Any step in the right direction would help immensely

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This is a pretty big request in one chunk. I'm sure you'll get better response if you break down your question into several parts, so that they can be tackled one after the other.

Also, we're happy to help you with your effort, but nobody here will be keen on developing a solution from scratch. This forum is about helping people learn how to use Excel, not a free development service.

Have you started any work on this project yet?
How far did you get?
Where are you stuck?

We can help you develop your own code, but if you want someone to code this for you all the way, you should try and find a commercial developer.