A common question I get asked is "why is my bokashi bin not producing liquid?"
The answer is simple.
The juice will really depend on how wet the ingredients are. If you are putting in things with a high moisture content, like watermelon, tea pot washings, fruit, then a lot of liquid will break down from it. If you are putting in drier things like rice, meat offcuts, carrots etc, then they have much lower moisture content.
You can compact all the ingredients down with something like a potato masher to squeeze out any liquid, and I highly recommend rinsing your tea leaves/coffee grinds into it to run it a bit wetter if you want to get some liquid probiotic to then water down and use on the garden.
Here's a great little clip on decanting and diluting your liquid once you make enough.