Any database file will become a 'very large file after data is added'. The data makes up the largest fraction of the file. With FileMaker, like most other applications, you have the application--the executable database engine you use to both create the database and to open and run it and you have the data file you created with your tables, layouts and scripts.
When you host the database file over a network, you host the database file you created with FileMaker Pro or FileMaker Server. The clients then use an application to access the hosted database. That application can be an installation of FileMaker Pro, or it can be a web browser application if you have set up the file with Instant or Custom Web Publishing (IWP or CWP).
Your clients cannot use a runtime FileMaker application created with FileMaker Advanced to access the hosted database.