My approver is saying that they haven't gotten the notification to approve my timesheet

Check the junk/spam folder or contact supportaus@oncoreservices.com

Quite often, automated emails from Oncore land in junk/spam. Have your approver check their Junk/Spam folder to see whether they have landed there (the email will be from supportaus@oncoreservices.com); or have them contact us directly via supportaus@oncoreservices.com and we can reissue their login details.