This example is for https://www.alphavantage.co/documentation/
You should be able to just paste this into your browser: https://www.alphavantage.co/query?function=DIGITAL_CURRENCY_WEEKLY&symbol=BTC&market=CNY&apikey=demo
Result: { "Error Message": "Invalid API call. Please retry or visit the documentation (https://www.alphavantage.co/documentation/) for DIGITAL_CURRENCY_WEEKLY." }
Is the API down or has the documentation changed?
Testing with my free api key, also fails. I've also tried it with a VPN so I don't think my IP is being blocked.
At least one other API call is working so I can confirm the server(s) is not down.