Hello,
Thanks for providing a view of your logs. Your API key is masked in the logs with ? characters intentionally. This is so that if the logs get stolen, any sensitive information is not in there.
You can view your api key with wp-cli: wp option get wallets_fiat_fixerio_key
I have signed up for a new apilayer key and I gοt the same result as you. Turns out that the old fixer.io keys are handled differently to the new apilayer keys.
I will upload a fix shortly.
Thank you for finding this issue, I never would have found it because I was using my old key and hadn’t realized that things have changed since then.