THere is no standard "start file" this could be a fileMaker file created by the programmer or it can also be a file that uses a URL to open the database.
If all the start file does is open the file on the server, you can easily create your own. It's not at all difficult.
Create a new database file. Create a script, it need not have more than one step, Open File. WHen you set up the Open File settings, use open remote to link to the file on the new server location. AT your option, you can add one more step to close the starter file.
Then open File Options and specify that this script run each time the file is opened.
That's the basics. Double click the file and it opens the hosted file on the server. If the server DB is password protected, the next thing you'll see is a log in dialog asking for a password unless your system is set up to use Server Based Authentication instead of FileMaker's.
You can also open the file without any starter solution simply by launching FileMaker and using open remote to find the server and then select the hosted file that you want to open unless steps were taken by your programmer to specifically hide the hosted files.