The button you are about to click is inside android.webkit.WebView. In other words, the app under test is an Android hybrid app.

To identify WebView elements, you should switch into the WebView first.

Java code for automating hybrid apps:

Set<String> contextNames = driver.getContextHandles();
for (String contextName : contextNames) {
    System.out.println(contextName); //prints out something like NATIVE_APP, WEBVIEW_1
}

// Switching to webview
driver.context(contextNames.toArray()[1]); // set context to WEBVIEW_1

// do some web testing
String myText = driver.findElement(By.cssSelector(".green_button")).click();

// Switching back to NATIVE_APP
driver.context("NATIVE_APP");

// do more native testing if we want
driver.findElement(By.name("hello")).click();

driver.quit();

For more details, visit offical docs https://appium.io/docs/en/writing-running-appium/web/hybrid/

It looks like a hybrid app .You have to switch to web view context on execution.
For finding elements After launching the app you have to inspect using remote debugging.
https://developers.google.com/web/tools/chrome-devtools/remote-debugging

The xpath is:
‘hierarchy/android.widget.FrameLayout/android.widget.LinearLayout/android.widget.FrameLayout/android.widget.FrameLayout/android.webkit.WebView/android.webkit.WebView/android.view.View’

which could be simplified to ‘hierarchy//android.view.View’

but the error message is telling you not to use an xPath

I am writing the appium automation for android application, It does not have proper xpath, class name or ID.

Even in Image, you can clearly check that when I click on get started. It clicks whole frame. I have attached XML as well.

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<hierarchy index="0" class="hierarchy" rotation="0" width="1080" height="2040">
  <android.widget.FrameLayout index="0" package="com.novo.android.dev" class="android.widget.FrameLayout" text="" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,0][1080,2040]" displayed="true">
    <android.widget.LinearLayout index="0" package="com.novo.android.dev" class="android.widget.LinearLayout" text="" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,0][1080,2040]" displayed="true">
      <android.widget.FrameLayout index="0" package="com.novo.android.dev" class="android.widget.FrameLayout" text="" resource-id="android:id/content" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,60][1080,2040]" displayed="true">
        <android.widget.FrameLayout index="0" package="com.novo.android.dev" class="android.widget.FrameLayout" text="" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,60][1080,2040]" displayed="true">
          <android.webkit.WebView index="0" package="com.novo.android.dev" class="android.webkit.WebView" text="" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,60][1080,2040]" displayed="true">
            <android.webkit.WebView index="0" package="com.novo.android.dev" class="android.webkit.WebView" text="Plaid - Securely Connect" checkable="false" checked="false" clickable="false" enabled="true" focusable="true" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,60][1080,2040]" displayed="true">
              <android.view.View index="0" package="com.novo.android.dev" class="android.view.View" text="" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[0,60][1080,2040]" displayed="true" />
            </android.webkit.WebView>
          </android.webkit.WebView>
          <android.widget.ProgressBar index="1" package="com.novo.android.dev" class="android.widget.ProgressBar" text="" resource-id="com.novo.android.dev:id/root_progress_bar" checkable="false" checked="false" clickable="false" enabled="true" focusable="false" focused="false" long-clickable="false" password="false" scrollable="false" selected="false" bounds="[480,990][600,1110]" displayed="true" />
        </android.widget.FrameLayout>
      </android.widget.FrameLayout>
    </android.widget.LinearLayout>
  </android.widget.FrameLayout>
</hierarchy>