
Hi @Anonymous,
Regarding your question on how to add a Flow to a PowerApp you have a simple guide that explains this in detail on our documentation.
This even shows how you can add a Flow as a OnSelect action in a button here.
For the the second issue you state that it is sending each entry "individually". What is the goal in this situation? What are the item updates that you are listening to in order to begin the approval processes?
You have a connector on Flow that can assist you in the creation of approvals as seen bellow:
You can consult our documentation on automatizing approval processes here.
Hope this reply was useful to you!
Regards,
Ricardo