You've done an excellent job at creating and setting up the custom form. There is one last step when you add/create a custom form - you must make it a "Sub-Menu" so that when people click on your "FORMS" menu, this new custom form will appear (otherwise it is just a form/page in the ether space).
To create a sub-menu for a custom form:
1. Navigate to the WEBSITE module >MENUS.
2. To the right of the FORMS Menu, click on the options icon > ADD SUBMENU.
3. The "Create Menu" box will appear. Type in the desired menu title (this is usually the same name as your custom form) and click on the pull down menu for "Links to" - when the list appears, click on the name of your custom form.
4. Then click "SAVE" button.
Now when you go to your website, you will see the FORMS menu, the sub-menu's listing all your specific forms and custom forms and you can click on the custom form and those clients you've assigned to the custom form will be able to access this custom form and submit their answers.