You can request a new invitation email at this link. This will only send you an invitation if one has previously been sent to you.
If afterwards you still haven't receive this invitation try these steps:
Check your spam folder
Make sure you're setup to accept emails from [email protected]
Confirm directly with your client that they've sent the invitation
Often clients will send invitations in waves across several days
Confirm directly with your client which email address they invited
A common issue we see is a mismatch in expectations here. Your client can confirm what email was invited.