If you wish to make the collection private, you can do so globally by applying a visibility rule to the collection single template. Navigate to the template then click on the page settings icon in the bottom left then Voxel > Visibility > Show If > Edit Rules > Add Condition > Choose Condition > User is author of current post. This will allow only those who create the collection to view it.
BONUS:
If you want to go one step further, you can add a switcher to the collection field and allow the user to turn on and off public mode dynamically. This would require you to add Dynamic Tag > Switcher > Unchecked or Checked depending on how you setup the switcher field in the fields.
Video tutorial here: