I may be misunderstanding the problem but I have the exact same setup and it works fine.
I think you might be missing a plugin to get to the setup for the user configuration. The Users are configured in the server manager local users and groups option. It is a pretty easy to follow setup from there. This can be done on a one-off Windows Server Box using just a Workgroup. No Domain needed.
It is easier to create a groups first for each User type and configure the Group Profiles permissions. Then changing anything is done to everyone by changing the levels of the group they belong to.
2008R2 was a pretty easy OS when choosing from all the MS Server options. You might even find that Windows 7 Ultimate (and maybe Pro) could do anything you need without the expense of CAL's. Depends on what you are using it for.
Please take the above with a "grain of salt" as I am speaking from personal experiences only. Your results may vary.

I can tell you the configuration changes I had to make to get mine to work as needed on a "Workgroup" instead of a "Domain" though.
PPS: Final note on your FTP setup: You are not alone! Try a Google Search and you will find Many people with the same problems. Posted on this Forum is one that had me hopeful till I got to the very end where you are shown that what you created was a "workgroup place", not a drive letter. For many people this may be all you need. B ut good luck if you need a Drive Letter associated with it. In truth, I am still working on it myself as it is a requirement for another program to use.
If you just want it to work and don't mind spending a few dollars for the ease of setup, I recommend "WEBDRIVE". It seems to work on everything I tried it with. FTPUSE is another that some say they have gotten to work but I have not had any luck with it at all. It is an OLD program (2009) and if you try it and get results, please post me or let others know here.
NETDRIVE is the third in the field and I was not very pleased with it. It might work if you could figure out what your particular needs are but they don't do a lot to help. Webdrive either connects right away or helps you find what changes you need to make to get it to work. It remembers the configuration and can be set to load them on Startup.
Please note that this is using FTP, not SFTP nor FTPS. As long as you know this going in. There are ways to use the secure versions but I advise getting normal FTP to work first.