After install, I cannot load the company file from the network.

Can you open the sample file?

It's wonderful to have you here in the Community, @chrisk66. Sharing a folder allows other computer to access files. I'm here to provide insights into setting up the Multi-User mode in QuickBooks Desktop (QBDT).
 

Have you encountered any error messages while activating Multi-User Mode? Providing additional details or screenshots of the issues you're facing would greatly assist us in troubleshooting and resolving them efficiently.

Let's double-check the mapping of your server or Host computer as a network drive. Then, set up computers for multi-user mode and specify the folder where the company file is stored.

Once the folder is ready, use the Database Server Manager, a tool designed to help handle database access issues in multi-user environments, to scan the folder. This ensures smoother file access across your network.

Lastly, enable hosting on your server computer:

1. Go to the File menu and select Utilities.
2. Choose Host Multi-User Access.
3. Click Yes to confirm.
    

For future reference, I've included detailed resources on how to add user with a specific role to manage your books: Create and manage users  and roles in QuickBooks Desktop Enterprise.
 

If you need any additional help or have queries as you proceed in multi-user set up, please don't hesitate to get in touch. I'm here to provide you with full support every step of the way.

Make sure that your network drives are properly mapped and accessible from the Windows 11 PC. Verify that both the server and the PC are on the same network, and ensure that the QuickBooks Database Server Manager is installed on the server. Also, check if you have proper permissions to access the network drives.

Hope! it would be helpful.