Sorry to hear about the trouble, we'll try our best to help you with it. Could you please try the steps shared below:
If this doesn't help, please share a few more details like:
Thanks for getting back to me so promptly!
Yesterday, when I encountered this issue, I logged out of Adobe XD and CC Desktop app, and even restarted my laptop a few times, but to no avail.
However, earlier today it worked and I was able to create a public link and share it with my colleagues.
Looks like it was a temporary issue like the one that happened around mid-March 2020 and was reported by multiple people on this forum.