Has this ever happened to you – you’re trying to share your Google Calendar with someone outside of your business and the only option you have is ‘See only free/busy’? But when you share internally there’s no problem?
Essentially what’s happened here is the G Suite administrator has limited how you can share your calendar with external people to the lowest level.
If you want to be able to share more details about your calendar with people outside your business then you’ll need to speak with your G Suite administrator and ask them to loosen the sharing permissions.
If they’re not sure how to do that (or if you’re the administrator and you’re not sure how to do it!) then this help article walks you through each step: https://support.google.com/a/answer/60765?hl=en
It can take up to 24 hours for the changes to take effect but after that you’ll be able to share your calendar as you wish.