Hey @Rbray! To do this, you'll actually want to create a single Zap with the following steps:
- FastField Mobile Forms "New Form Submission" Trigger
- Box "Create Folder" Action
- Box "Upload File" Action
When you get to step 3, Box will ask you to choose a folder. Instead of selecting one from the drop-down, you'll need to choose the "Use a Custom Value" option from the bottom of the drop-down list. That will allow you to insert the "Folder ID" field from step 2 to dynamically upload files to the folder you just created. 
Let us know if that's helpful and if you have any other questions around this!