For clients on a dedicated server we support SSH. SSH is a much more secure version of FTP but basically the same concept. Again, this is ONLY for clients who are paying for a dedicated server. And any connections are restricted to their IP address block.
Remember that Tendenci is open source so if you want less security and easier access, you can self host and control your own destiny entirely. We just take security seriously and in a shared environment it's too risky to put everyone at risk.
If your goal is to back up your site, set up an AWS account and provide us the credentials and we can configure your site to backup directly to your S3 bucket (Support charges to configure it do apply, but that's it.)