Here’s something incredibly annoying! If you have an Office365 account you cannot create a Microsoft account for use with Skype using that email address.
The answer to this conundrum is simple! We just used one of our unused domains, created email forwarders for each member of staff then registered with Skype using this. eg firstname.lastname@example.org forwards to my email@example.com account. This way password resets etc can come to your work email account etc too.