You have to upload your web project to cpanel so that you would connect your app with your admin panel.
Follow the below steps
Click on the "File Manager.
Then Click on the "public_html" folder.
Now select "www" which is placed in "public_html".
Open backend folder from AliXpress which you download from CodeCanyon then you can see compressed alixpress_app.zip.
Click on upload button & select your_project zip file from backend folder.
It would be uploaded successfully.