Power BI Help Writing Data Back to SQL Table using Power Apps

We have several Power BI reports that mostly talk to an on-prem SQL database using the gateway software from Microsoft. I want to be able to have Power apps that allow for editing of some data using online Power Apps forms. As per https://www.youtube.com/watch?v=uPHwjPRnRwE - but I am having problems getting access to the data from the power bi app designer. Would like to see if I can share screen and get some assistance with this task.