In order to see any entities or mobs in Vox-L, you first need to buy the Vox-L artifact from our artifacts shop.
At the top of the LearnToMod homepage, click the artifacts link at the top, then press the purple button to remove the default filter. Click on the superflat world, and 'Download Vox-L Alpha'. Once you open the downloaded app, you should be taken to the LearnToMod page within the app to sign in.
The Vox-L game should be the first thing you can buy.