Those instructions are out of date, and have been since Feb 10 when the Custom Token Markers were released to the Marketplace. Unfortunately, the Zendesk Help article seems to be turning up with a 404 error. Properly formatted Custom Token Marker sets should not need to be downloaded anymore. If you have purchased the set, it should be available for choosing when you choose "add a set" from your home page. That particular set, if it is the one I am thinking of, was created long before the CTM feature was created (hence their talk of a custom script), but I thought they had been converted. I have reported the missing help article to the dev team. It should be: <a href="https://roll20.zendesk.com/hc/en-us/articles/360041536313-Token-Marker-Sets" rel="nofollow">https://roll20.zendesk.com/hc/en-us/articles/360041536313-Token-Marker-Sets</a>