In case, you have made any changes on the code, css or js file. Backup them first so you don't lose your work. Download them or take a note of what you have changed.
public/uploads - here are the uploaded images ( you can zip it and move it somewhere )
public/byadmin - here are the custom CSS entered from the admin - if you have any
.env ( Required - Download it)
modified - created language files - resource/lang/YOUR_LOCALE
Download the code from CodeCanyon and directly upload it on your hosting, in the same place where your existing site is.
Extract the zip files. Overwriting old files.
Go once again to your file manager and upload your old .env file
Create an empty file named installed in /storage
Here, if there are migrations for the database to be done, will be run.