If you simply want to pin recipes to your calendar (without having to chose the specific day or meal for each), use the 'Quick Schedule' feature. This feature is useful if you just want to generate a grocery list.
You can do it from your Cookbook or while viewing a Recipe Collection, where you can check the boxes of the recipes you'd like to add to this week's (or next week's) meal plan calendar.
When you're done choosing the recipes you'd like to plan for, simply click 'Quick Schedule' - which will pop up at the bottom of the page as soon as you check off a recipe checkbox.
Choose if you'd like to add the recipe(s) to this week or next week's calendar, and then select who in your household will be eating those meals.
The meals will be added to your calendar (go to your Schedule page to see this) and be listed under 'Meals with no day selected'.
If you wish, you can then drag and drop those recipes into the appropriate day/meal slots, or just keep them as is - regardless, your automatic grocery list will be generated below (and of course also accessible by clicking 'Shop'.)