Nope! You can give credentials to anyone at any time. If a person is not already on Digitalme.Credly, all you need is their email address to give them credentials. Or, if you are signed in using your Facebook or LinkedIn account, you can give credentials to any of your contacts on either service.
When you send someone a credential, they will receive an email notification and from there they can either sign in to accept the credential or easily create a new account if they are new to Digitalme.Credly. Either way, the credential you sent them will be waiting for them to accept when the next login with an account that they have associated with the email address you used to issue the credential.