element-android/vector/src/main/res/layout/activity_jitsi.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/jitsi_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@android:color/black">

    <!-- Note: A org.jitsi.meet.sdk.JitsiMeetView will be added here and so add tools:ignore="UselessParent" -->

    <LinearLayout
        android:id="@+id/jitsi_progress_layout"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        android:gravity="center"
        android:orientation="vertical"
        tools:ignore="UselessParent">

        <ProgressBar
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:indeterminate="true" />

    </LinearLayout>

</FrameLayout>