Deadlines for applications vs required materials

Hi everyone, I hope LSATs are going well and no one is (too) stressed out! I noticed today while working on an essay the Northwestern has two different deadlines for Early Decision applications. Per their website:

October 15

• Deadline for receipt of JD Early Decision (ED) application

• JD Early Decision (ED) application closes 

October 31

• Deadline for receipt of all JD Early Decision (ED) required materials 

What does this mean? I'm especially worried about the Kira interview, but does this mean I could theoretically apply before the 15th but not complete that interview (or for another example, get my letters of recommendation in) until the 31st? I've tried looking this up and am running in circles. Thanks!!