Using A.Box.Com For Accessibility

This question is in continuation of my previous question,  https://community.box.com/t5/Platform-and-Development-Forum/Box-as-a-central-storage/m-p/58894. 

That question was solved very nicely. When I was trying to implement that solution, I hit a dead end with usage of app-users .   

 I have decided that I will create app-user, for each person who downloads my app. 

Now, this app user has been assigned an initial access token. Then, I am having  difficulty in understanding how to authenticate this app user and make api calls from that, after the first time.

BoxAuthentication.BoxAuthenticationInfo info = new BoxAuthentication.BoxAuthenticationInfo();
// Populate info with as much information known as possible. If the access token is not provided the refresh provider implementation's launchAuthUi method will be invoked.
info.setAccessToken("the first access token");

BoxSession session = new BoxSession(context, info, REFRESH_PROVIDER_IMPL);
session.authenticate();

I came across this in the android box-sdk(https://github.com/box/box-android-sdk/blob/master/doc/AppUsers.md), where I could authenticate using the access token obtained in the beginning. What access token is this referring to? Here, I don't know what to do with REFRESH_PROVIDER_IMPL.

When I do it using normal users using OAuth2, I get 2 tokens an access token and a refresh, and using the refresh token, I can get a new access token. But with JWT I am getting confused.

https://github.com/box/box-android-sdk/issues/348

The above link says that the user has to manually login compulsorily. Is this required? My idea was to create an app user by running a python script on the server, using the enterprise information, and then adding the login of this app-user as collaborator to a folder. Then from my app, using this app user created, I want to upload stuff. Is this possible?

Can you help me out please?

Thanks a lot in advance!