I was able to fix the error on my MacBook Pro with the advise above from Scott on the MathWorks Installation & Licensing Support team. I've added a few tips and step by step clarifications for others that may have the same issue.
I was receiving the -9 error. I'm running OS X Yosemite 10.10.5
It seems that you need to know which user on your Mac you are using. To find this out open a terminal window and type "whoami". Copy that result. You will need that at last step of the activation process.
I installed MATLAB in the /Applications folder.
In the terminal window go to wherever you installed MATLAB and find the bin sub-directory. For me this was /Applications/MATLAB_R2016b.app/bin
In the terminal I ran the activation script again by typing "./activate_matlab.sh"
Then I went through the steps "Login to MathWorks" [email/password] >> Next Selected the pre-selected license. >> Next Provide a user name/Login Name: (Paste the user name that you copied when you ran whoami above.)
Then open a new finder window go to Applications and try to run MATLAB_R2016b. It opened this time without errors hope this helps.