When using the script that’s included with Painterly, I get errors.
Go to After Effects -> Preferences -> Scripting and Expressions and make sure that the “Allow Scripts to Write Files and Access Network” checkbox is checked.
Without this, After Effects is not able to write to the Painterly Preferences file, which it needs to be able to do. This preference should generally be enabled. Most third party scripts will not work if you don’t have it enabled.