Paid members can use both proftp.drivehq.com and ftp.drivehq.com. Free members can only use ftp.drivehq.com. The information is documented in our FTP features page and online help pages. Please visit our FTP Hosting feature page and read the FAQs carefully.
Free members are limited to 2 concurrent FTP connections. Paid members can have a lot more concurrent FTP connections. However, the max number of concurrent FTP connections is associated with your account's max storage space.
In the group account case, if you store all data in the main account and don't allocate storage space to your sub-users, then you can have quite a lot of concurrent FTP connections accessing your shared folders by your subusers.
If you allocate storage space to a sub-user and store data in the subuser's account, then the max number of concurrent FTP connections is determined by the amount of storage space you allocated to the sub-user. If you only allocate 1 GB storage space to a sub-user, then only 2 people can log on to the subuser account via FTP at the same time. To increase the limit, please allocate more storage space to the sub-user.