The Home and Enterprise versions are free so if you want ClearOS go get it. Is this just a simple storage/file push server? Im with nordlead...I use Filezilla server/client. Easy user/pw set up and highly expandable.
This guide is what I used to install my Linux server at home a few years ago, not sure if its still good but try it.
Do you have a static IP address from your ISP?
If you don't or you don't know I would recommend you stop right there.
As without a static IP address you'd have to tell all the users your IP everytime you reboot your router. Which will become a pain in the neck if you have 40 users.
On the basis you have a static IP address install XAMPP (or just FileZilla), follow the installation through. Create the logins, setup home directories then just give the users the details.
In truth if I was setting up an ftp server at my house I'd want to use a device similar to raspberry pi attached to an external HDD. That way I could leave it on 24/7 without worrying about noise or the cost.
You don't need a static IP. Check out dyndns.org for a free DNS service. My TP-Link router can actually tell dyndns.org whenever the IP changes.
My home server draws 30W at idle, and is wisper silent since it is an Atom D525 with a single fan on the processor. I'm positive I could replace it with a giant heatsink if I wanted to but it isn't worth the investment and it would void the warranty since it was an all-in-one mini-ITX board.
The rasberry pi wouldn't make a very good server. External USB2.0 is slow and the Ethernet is limited to USB dongles or 10/100Mbps. It would be really cheap (if it is actually $35 for the Ethernet enabled version), but you'd be limited to a single external HDD without shelling out more cash for hubs.
i have a dyndns free DNS name.. so thats no prob. i run my own wow server for just me and my friends. but it seems im strugling with the FTP... sigh
i dont care about the fan, power, or what so ever. its for a buisness where i work. i want to make a FTP for all the employees. where they can upload work. (word files and excel) and download them. where ever they want... catch my rithel?