Guest User profile, go to Settings | General. Under Guest User Profile, click the profile name. Click Enabled Flow Access | Edit.
If you cannot find the guest profile, here are the steps on how to navigate to guest profile.
Navigate to setup => All Sites => select desired site => Experience Builder and go to Settings.
On the General tab in the experience builder, click on guest user profile. It will take user to respective profile under setup.
Under Enabled Flow Access, click Edit.
Choose required flows from the Available Flows column and add them to the Enabled Flows column.
Save your work.
