If you're unable to set up your free Workplace account for Oculus for Business, it could be for one of the following reasons:
Your invitation has expired.
Oculus for Business welcome emails contain a link to set up your free Oculus for Business acount. These links expire after 90 days. Check your email for a new invite from Oculus for Business, and if you don't see one, please contact Support.
You already created a Workplace acount.
If you've already created a Workplace account from your Oculus for Business welcome email, you will need to log into your Workplace account to finish setting up the account. Check your email for a message containing your Workplace account login details.