a week ago download this version of docker, the question is that docker should work only with windows 10, however this version in peculiar for two things, I can run from a windows 7 and second because I do not find a similar in google with a version '-dev'.This version allows me to work with docker normally?
If it works in Windows 7 you must have downloaded Docker Toolbox because as you say Docker for Windows works only in Windows 10 for the Hyper-V support you need.
Docker Toolbox you can use it perfectly in Windows 7 in its final version does not have to be Dev.
Now if what I say is not what you are using please post here how you downloaded it and how you are using it to see.
Greetings