Return Value to Different Line with Possible Duplicate Information [closed]

In Google Sheets, I need to extract values of D in specific rows and insert them into column I where appropriate.

See link below. Here is an explanation of what I have so far in the spreadsheet:

1. Raw data that I need to modify is in columns A:D.
2. I have an ArrayFormula in E2 that pulls rows from A:D where C is not blank.
3. Where C is blank, I need D to be inserted into I where E:F match A:C. <---This is what I can't figure out.

I'm not married to the formula in E2 if there is a more-efficient way to grab all of the information in one shot. Here's a sample of the data, and what I have so far.

I highlighted groups to show that there are sometimes duplicates or triplicates of the Zone. The value of D should go in I in line with the first iteration of the matching Route/Zone.

https://docs.google.com/spreadsheets/d/1xIum-fNKfdS4XWtpaHHJpluTUA3kUEDDMzStQsSxyi4/edit?usp=sharing