How do I go about setting up sub-accounts?

To add a sub-account, you need to have a multi-seat plan.

Easily add and administer sub-accounts, or control their access, with just a few clicks. Allocate downloads from your administrative account to any member of your team. Take files back at any time, or reassign them to other users, depending on your needs. Set the auto-refill if you want.

To create a sub-account, please go to Team -> Create new user.