Ok.. the TC can be used as network hard drive.. you can put all your files on it.
BUT.. please think carefully about this.
The Time Capsule is designed for Time Machine as backup target.. principally for wireless laptops.
If you use large files remotely.. and by wireless .. they will take forever to load.. the TC is slow but wireless is even slower.
It is not a giant USB.. but you can buy a cheap USB drive now that we have USB3 on MBP latest version?? it is fast and cheap and a local drive.
Time Capsule has no raid.. no backup.. no protection against failure of the disk or the device or accidental deletion or corruption. That makes it unsuitable as a file store.
Apple do not sell a file store..
You can buy a true NAS.. Synology or QNAP.. Netgear also make some good ones.
Or you can get a Mac Mini and run it as file store.. with or without a server version OS.
Anything that offers you proper backup and fast file transfer.. which the TC fails to do.
I also use TC as NAS and as TM Backup.
The TM backups my two iMacs, and the TC provides files to both macs, like films, music etc.
So to be safe, I use another Harddisk, I connect it to the TC and I backup also these files from the NAS to the Harddisk. I use iBackup for this task, once a week.
And I think I found a way to limit the size of the sparsebundle on the TC. Because normally it will grow and grow and you won't have space for other things on the TC.
Watch the tutorial, if you like to know how: