How to make an app user to access another app's content in a efficient way?

 that is pretty much the way to go, through collaboration.

I'd love to know what you are trying to achieve though, and maybe there's a different way to go about this. Do you control both of these apps? What is stopping your application from authenticate as an app user in the other enterprise?

Hi  ,

   Thanks for ur concern. We do have full control of both Box apps. Now we trying to using SDK to copy folder & change owner one by one. The bad is that will last for several days since we have 80,000 folders need to process. We need a better solution here, Tks! 

 I'm sorry to hear about this. I can't help you directly here without looking into your account, but feel free to reach out through our support team who can look into your specific account.

The best solution I can think of is to invite the other app user to your folder, then make them the owner, and then from the other app user remove the original user as a collaborator. Is this what you are doing already?

To follow up, here are our support options: support.box.com

Hi @cebba, Thanks for ur support here. I think ur idea is a good way. And we found the key is to reduce API interaction times as few as possible that would lower the time cost. We boost the progress by process dozens of folders one time. Seems good. Thanks again!