Welcome to the community @mmm286. The VM only requires 8GB of RAM if you are using Cloudera Express. If you are using the CDH default (without Cloudera Manager) it only requires 4GB of RAM for the VM. You could also use something like Amazon Web Services to spin up a cluster but there are costs involved there. For your specific needs of preparing for CCA-500 the CDH default VM shoudl work well with your amount of RAM.
There are other requirements for the VM such as a 64bit processor. I suggest checking out our article on How to Setup a Cloudera QuickStart Virtual Machine to ease you into it and in case you run into any issues.
I have the same problem, I can't install Cloudera Express.
The problem is I don't see any tutorials for that CDH(all of them assume that Cloudera Manager is installed), I can't run Hadoop, HUE, etc.
I'm new with Hadoop and I can't proceed futher.
Could you give me an advice what should I do to run hadoop and lets say to count words.