HOW TO MERGE GAME FROM UNITY ENGINE TO ANDROID STUDIO APPLICATION PROJECT?

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I have an application built with Android Studio, but my client asked to make a game with Unity Engine (I hired someone else to make the game, I got the source code, apk and unitypackage for the game I requested) but I don't know (I even asked this to CoPilot Think Deeper)... 

Among other things, it requires a communication method between java code (my project) and C# (unity game) using UnityPlayer.UnitySendMessage(“GameObjectName”, “MethodName”, “Message”); and such.

I still don't understand to move/switch the page from the home view of my application to the game view (see in the screenshot I linked, it is the user's page to choose/start from Pre-Test first, there are 3 menus... Pre-test, Game (here is where the game page is transferred), and finally Post-test. 

For more details on the meaning of “Switching Pages to Unity Games that are exported and incorporated/integrated into my Android Studio Project” can be seen in the VIDEO LINK.
YOU CAN SEE THE PROJECT STRUCTURE OF MY STUDY ANDROID APPLICATION FOLDER HERE | HERE.

DISC: I don't know how to link the image here, so I used an external link from outside.

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why do you wanna merge it , you can build android directly from unity

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and if oyu need a communication between react or java and unity there is some tools you can find on github that can link certain messages or actions between the two languages

[56]

why do you wanna merge it , you can build android directly from unity

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and if oyu need a communication between react or java and unity there is some tools you can find on github that can link certain messages or actions between the two languages

because the application is an educational element for collecting thesis data points combined with games as an interactive media for these children.
The application that I made in android studio will have 2 features, features for collecting thesis data (pre-test, post-test, educational material) and interactive media, namely games built with Unity Engine.