Problems with Microsoft Planner and Calendar synchronization

I have followed all the steps described in this tutorial: https://support.microsoft.com/es-es/office/ver-la-programaci%C3%B3n-de-planner-en-el-calendario-de-outlook-9f0eb699-cf2b-45be-a464-83f005d82547

When I click on add plan to Calendar, the calendar subscription tab does not appear.

I also tried to include the calendar from the directory, but that didn't work either.