Shared Storage Solutions

We already are clients of the basic hosting services. We have our business website running on your services, as well as email. We need a small shared drive for our business, with no more than a handful of concurrent users and nothing unusual with regards to file sizes or formats (no video). We can handle creating a shared drive on the business' network on our own, but we would like to have the ability to access this from outside our network, with security measures, possibly through a subdomain.

What options can you recommend with our existing service? obviously we could setup a VPS, but I think that would be overkill for this small implementation.

Thank you,

J.M.