Create a file will raise this error "Access denied. 403", although i am the site admin

I have an AddPicture Control, and inside the OnChange i am calling a workflow as follow:-

    PopulateWorkOrderPictures.Run("Before","Posting",TextInputPicNoteBefore.Text,varWorkOrder.ID,varWorkOrder.RelatedProcessID,


{
         contentBytes: UploadedImage1.Image,
         name: AddMediaButton1.FileName
     })

here is the flow definition:-

but i am getting Access Denied error 403. i can confirm that the "Folder Path" inside the "Create file" action is valid and it is as follow:-

AttachmentDocuments/11111111-23-12-2023-posting/Before

and also i am the site admin and i am using power apps using my email, which have full control on everything.. any advice why i am getting this error?