Can i get detailed steps on how to integrate the apk. I am closely following the official build guide for pixel 8a but i am stuck. Without this apk i have successfully build and flashed the OS into my device

I have mentioned MyApp in handheld_product.mk and my android.mk is as follow

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := MDMApk
LOCAL_MODULE_CLASS := APPS
LOCAL_SRC_FILES := MDMApk.apk
LOCAL_CERTIFICATE := platform
LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
include $(BUILD_PREBUILT)

I want to know that do i need to do something more like to sign this apk with grapeheneOS or anything else. Please tell me.