Hello,
As you can see in the error message, the error is due to the exchange rate not being loaded for the available coins.
You should enable some exchange rates providers that carry the exchange rate with the coins you offer wallets for. Then, if your woocommerce base currency is a fiat currency, such as USD or EUR, you will also need to enable the fixer.io exchange rates provider, with an API key.
The plugin will then be able to figure out the prices of the products you are offering in those cryptocurrencies that you offer wallets for.
Hope this helps. Please let me know if you continue to face difficulties with this.
kind regards