I don't think you can install docker on Windows 7.
The install pre-requisite for docker is Windows 10 (or natively on Windows server 2016)
Please see this link which is the docker install for windows.
Here is the content from the page for posterity:
System Requirements:
- Windows 10 64bit: Pro, Enterprise or Education (1607 Anniversary Update, Build 14393 or later).
- Virtualization is enabled in BIOS. Typically, virtualization is enabled by default. This is different from having Hyper-V enabled. For more detail see Virtualization must be enabled in Troubleshooting.
- CPU SLAT-capable feature.
- At least 4GB of RAM.
If you are locked into Windows binaries, then I don't know of a good solution for you unless you upgrade to he latest Windows OS, but if you can run your code on Linux then you can either use a free Linux OS and host your container there, or if you really must, you can spin up a VM on your Win 7 machine to host linux and run your container.