What is the preferred technology stack to build a file storage application (web and mobile app) for 7Billion Users?

I am exploring technology stack items to put together to build a file storage application for 7Billion Users with an expectation of 50% concurrent users. Key deliverables –

1. Single file size can be up to 2GBs.
2. Each user gets 2TB space.
3. Each user can have unlimited number of files.
4. 3.5 billion users can be connected to this application at any given time.
5. User should be able to search their files (top 1000) by name, metadata in less than 3seconds.

I am hoping one or more experts can share thoughts on already proven choices. It will be great help for me to reconsider some of my partially considered pieces. Given are the items I am considering so far –

1. Database – Single Store, MongoDB or CouchDB
2. Application server -??
3. UI – React or Angular

I am also considering some other factors (mentioned below) to get to my final goal. So far, my understanding is there is no such technology stack which is equipped for this job out of box, I could be wrong though. To build this kind of application will require given items or more

1. Load balancing.
2. High-level caching.
3. Bigger and faster servers with more resources (e.g., CPU and memory)
4. Faster disks (e.g., SSDs)
5. Scalable databases.
6. Bandwidth/Network upgrades.
7. Type of application server

Any experienced advice on any of above-mentioned items will be helpful.