How to populate dimensions with no matching columns?

Question

I'm working on a project for school and I'm new to the database design so I would appreciate any advice to learn the best practices.

I was giving a data source for a bank and my assignment is to create OLTP then DW. My OLTP is as follows

now I'm trying to populate these to the dimension tables but I was told that having the LoanNumber like this is redundant and also I can't have this column in all of the fact and dim tables for the next step. My questions are:

1. As far as I know, is that I need a matching column to do look up to or use the MERGE statement on to move the data to the DW. So what should I do in this case?

2. If I take off the LoanNumber column how would I join between these tables? should I replace it with and ID columns for each table, would that be a good thing?

the dim tables that I have the fact tables