Let us start by exporting your BBDOC file to Android.

A pop up will show up. You can either create your Bundle ID or in this instance, lets click continue to use the default ID.

It will then ask you to save to a location.

In this guide, I am using Android Studio 3.1.2.
Open Android Studio and select the below option.

And then browse through the location where you saved your exported file. Open the android folder and select build.gradle.

It will then start to build an android gradle project.

Once we have Android Studio opened, let us click Build then select Generate Signed APK.

It will then launch the below window. Click Create new.

In this window let us click the button highlighted below to select the location where you want to save your key.

In the sample image below, I selected the desktop and named the key "Sample Key". Make sure that jks is selected. Then click OK.

Next step is to fill the fields with necessary information. Then click OK.

It will then launch the window below. Click Next.

Make sure that V2 is checked then click Finish.

It may take a few minutes to create your APK. Once done, you can click the locate link on the notification box, or if it did not notify, you can click Event Log on the lower right corner of Android Studio.

From there you will see the locate link. Click on the link to show your created APK.

Following instructions above, this is where my APK is saved.

IMPORTANT NOTE:
Remember to save a copy of your keystore information/password as that will need to be used for any updates of the application once uploaded on the play store.