What does “We are unable to match against ….” mean?

If your company does not use activation codes, then the details which you provide when you register will be compared to those your company has entered when they created your account. This is a security check so they must match exactly, otherwise you will see the message “We are unable to match against the information provided by your organisation”. Check with your HR team as to what they entered when they created your account.
Hint: Most employers add new joiner accounts in monthly or weekly batches, so check with your HR team whether your account has been created yet.