If you have installed jmeter with homebrew can run these commands in terminal
brew install jmeter
brew install jmeter --with-plugins
If you are running jmeter 3.2, you can found your jmeter CA Certificate here.
The simplest way to installing this certificate is by opening the directory and double clicking on the file. By default it will be added to your list for certificate but not trusted. If you right click you will have the option to trust where you will need to type in your machine password.