Many times an Unmoderated or Diary doesn't require you to use the Respondent calendar, however, you will still need to send an invitation to the Participant in the project dashboard.
This helps you track each participant in the project dashboard as they complete your study.
Here's how to do that:
Create a calendar. This will allow you to send the invites to your Participants. Your calendar doesn't have to be fancy, just enabled.
When you are ready to get started with your UX testing, in the Participant tab, click on the blue INVITE button for each Participant you want to include in your study. When the invitation pops up on the screen, put an alternate calendar link, or your company URL in the Use Another Meeting Service or Location field.
Finally, in the Add a Message or Special Instructions Box inform the Participant that they won't be booking time with you on the Respondent calendar, but they need to accept the invitation Respondent sends them via email or SMS in order to mark them Attended and Pay their incentive for participating in your study.
If you have a special project link for your UX study, paste it into the instructions box as well.
When the Participant accepts your invitation, they will see the special instructions and UX link, and their status will change to Mark as Attended.
When you receive their completed study, click Mark as Attended, and the button will update to Pay, and the Participant will move into the project payment tab.