I would suggest you to try with latest service pack that is SP10. Even if you have installed JDK 1.8 installed on your machine (i have the same on my Win10 system), you should be able to install.
Please try it and share your findings.
Note: This SP10 of SDK has sapjvm_7_jre folder in the mobile sdk installation but you really dont need to worry about it. Installer will take care of it by itself.
Regards,
JK