From this documentation: https://apps.odoo.com/apps/upload, in the question "How to set up an icon, cover image and description for your modules?", Official starter template link is mentioned. This link leads to a 404 error page. Is the page moved and what's the new address.
The official documentation page is actually outdated. It still links to 9.0 links while Odoo has changed the indexing and searching of apps on the appstore. The Point of Sale URL has become https://apps.odoo.com/apps/modules/category/Point of Sale/browse?series=12.0 and the CRM has become https://apps.odoo.com/apps/modules/category/Discuss/browse?series=12.0
I've logged an official ticket at Odoo so that they can resolve it.