Confusion on which tool to use to create SAPUI5

I am new to SAPUI5 but I need to make a copy and then change to the Sales Order Fulfillment (SOFM) SAPUI5 app.  We are on HANA Version 1503 on-premise.

After much research and reading to try to figure out what I need to do to change SOFM app, I think I need to use the WebIDE in the HANA Cloud (HCP) and cannot use Eclipse to do what I want to do.  First, do I really need to use the WebIDE on HCP to view the SOFM SAPUI5 app.  If so, how do I connect WebIDE to my HANA on-premise system?  If I can use Eclipse, how do I look at the SAPUI5 app in Eclipse.

I appreciate any help to learn how to get started.

Thanks.