I no longer have a free account so I don't know how the page looks for you, for me there is a button to add credits. I don't know why they didn't add the $5 to your account when you opened it, maybe they changed something or it's a bug.
together.ai still gives you free credits when you sign up (I hope), and groq.com is free (with rate limit). Both offer good models (try Llama 3 70b) and are very fast.