Happy you are dipping your toes in. First rule - have fun.

There will be spoilers below. When I have to prepare actual scenarios I tend to start with the end, what the goal is. From there I look at how the adventurers can get there. For this adventure it is the recipe, so locate that and its immediate obstacles.

Then I start from the beginning and read through the adventure to get a feel for its flavour. For example where does it land on the goofy <-> serious spectrum. Make notes of these flavours and try to reinforce them during play, by that I mean to bring them up and/or exemplify them. Such as the grumpy tree outside.

Now time for actual "room" (location) prep. For you the important parts are in the paragraphs under the boxed text. There you find monsters, suggested skill checks etc. But I don't look at those for now, rather I figure out the goal of each location. What do the adventurers get in this location that brings them forward? Location 1 for example. There the adventurers can learn there are goblins inside that doesn't use the front door. And that old Grammy used to talk to the dryads (where are the dryads??? In the orchard) who may know more. Also figure out how they are supposed to learn this (talking to the tree, how is it revealed the tree can talk?). And finally to what other locations does this location lead to, and how.

By doing all that I end up with the adventure reformatted in a useable format for me. The information I need ready to be used.

As for foundry I bet you can find videos floating around. While looking at them slap up a game and roll up a character. Test out the sheet so you know how it functions and can assist the rest of your group.

DnD specific stuff. Make sure your players knows their characters, any casters how their spells work etc. And when in doubt, as in the characters try something risky where failure brings the adventure forward, ask for a roll. Just pick a skill that makers sense vs a DC of 12-15 (adventure seems to be in that range).

I have probably missed things or explained things badly here and there sp just ask any followup questions you have.