GroupName / Username to Use for QS User in Row-Level Security Dataset

I’m attempting to share a Dataset with another Quicksight user, which has been secured by row-level security. In order for that user to view the data, I need to first identify them in the RLS dataset’s GroupName column so that I can grant them access to specifics rows by Account ID. I’ve tried adding their Quicksight username, but that doesn’t seem to be working. This is what my RLS dataset looks like:
±------------------------------±------------+
| GroupName | AccountID |
±------------------------------±------------+
| QuicksightUser’sUsername | 1, 2, 3, 4 |
±------------------------------±------------+

This format is working successfully in an embedding scenario, where I’m explicitly passing in a GroupName as part of the Dashboard call, which implies that I just don’t have the correct GroupName. What should I be using in my RLS dataset to identify the Quicksight user?

You need use UserArn in RLS dataset to identify the quicksight user.

Sample UserArn Format :
arn:aws:quicksight:::user//

Here is the workshop link to setup RLS on data set: