Invalid Credentials Dataflow + On-premise data gateway

Hello, community

I have been trying to set up a connection whereby I can upload files from my local drive to Power BI Dataflows using an on-premise data gateway. I have installed the gateway successfully and have it running online. However, it has been a challenge uploading my file (an Excel file) to Dataflow, which keeps complaining about credentials.

I created a connection name, but Power BI Service is not accepting the custom username and password I provided. When I click on "Skip test connection", it automatically generates a login credential for the Windows authentication type. It seems these credentials have been encrypted, as I don't have access to them. I was expecting it to automatically populate whenever I select the connection name in the process of uploading my local files to DataFlow; however, this is not the case, and whenever I provide a username and password of my own, it keeps returning an invalid connection.

I have tried solutions provided here, here, and here but all to no avail.

Kindly provide help on how I can scale through this phase. Thanks