Is it absolutely necessary to use the credit karma tracker after submitting my tax refund? In other words, can I skip it and get back to it at my leisure?

Please contact Credit Karma on their Contact Us page. 

Once your return is filed, TurboTax has no control over the processing of your return or the release of your refund.

Here are a couple FAQs to track your refund:
When will I get my federal tax refund?
How do I track my state refund?
Why does Where's My Refund say "approved" but TurboTax still says "accepted"?