To allow anonymous donations to be made on your donation forms, please follow the steps below.

In Luminate Online select Fundraising > Donation Management
Select All Donation Forms
Click Edit for the donation form you wish to add this functionality to
Click 3. Design Donor Screens
Click Edit for Donation Form
Select Anonymous Donation in the Select data elements to include in this form list
Click Add > 
Click Save Order and Edit Selected

Constituents will now be presented with the option of making their donations anonymous, when using this form. If you would like to adjust where this element appears on the form, you can select it in the Arrange the order of the selected data elements list, and use the up and down order buttons to alter its placement. When you have finished placing it, you can click the Save Order and Edit Selected button to save your changes.