In order to intercept HTTPS traffic from Firefox, it requires extra steps to install Proxyman CA into Firefox's Trust Store.
Before installing Proxyman CA on Java VMs, we have to install properly on your current mac machine.
Check out macOS Guideline:
If you've done this step, you can skip and start the next step.
Open Firefox's Preference panel (CMD+,)
Search Proxy and open the Proxy Setting
Select Auto Use System Proxy or manually hardcode the Proxy IP and Port
http://proxy.man/ssl on Firefox and download the certificate to your Download folder
2. Open Firefox's Preference (CMD+,) and open View Certificate window
3. Open the Authorities Tab and select Import button
4. Select Proxyman CA, which you've downloaded and Trust all.
5. Reload your page that you need intercepting. Enjoy!