Setting up FTP user/pw with SecureCRT

First off, I apologize if this should be posted in another section... I looked through the various board sections and couldn't make heads or tails of them.

My problem is this: I'm turning over a client's website management to the actual client after having updated it in-house for a while. We have our own username and password set up for FTP access, but that username gives access to the client's site as well as our own site and several others we're hosting. I needed to set up a new username and password that will only allow the client to get to their site, so I hopped on SecureCRT 3.3 (Windows), went through the normal procedure for adding an FTP name/pw, and got this message:

sh: useradd: command not found

Now I know other things in SecureCRT work fine because over the past year I've had no problems with things like password protecting a current site directory; it just seems like adding a user is giving me the problem. I've looked online for any answers and can't seem to find anything related to this, and I don't know enough about SecureCRT to really expand any further on the problem. Can anyone help with this?

m19