I think you might be hitting a bug. The conda commands the Dato Launcher depends on apparently has a known issue in newer versions of Anaconda (ver >2.4.1) on OSX. Since the Dato Launcher is trying to install into your existing Anaconda installation versus installing Anaconda itself, this might be the case.
First, check your Anaconda version, then try a workaround until we release an update to the Dato Launcher.
Check the existing version of Anaconda by executing
python --version at the root of your shell. Versions >=2.4.1 on OSX will likely face this issue you are experiencing.
You can manually create the conda environment 'dato-env' by executing the below command, then re-run the Dato Launcher to complete the installation.
conda create -n dato-env python=2.7 anaconda
Let me know if this works for you.