OK, thank you for the additional info.
I tested again with Monero 0.16.0.0 and I got the same result.
It appears my installation instructions are outdated, so please accept my apologies; hope you didn’t waste too much time on this. I have now updated the instructions on the adapter’s homepage.
Step 3: I have added the --no-zmq parameter to the monerod command, because now the daemon binds ZMQ to port 18082 by default, but we don’t need it. If you actually need to use ZMQ for a different application connecting to the same wallet, then you should use a different RPC port.
So, the full command would be:
monerod --rpc-bind-port 18081 --rpc-login monero_daemon_user:monero_daemon_pass --no-zmq
Step 4: You should start the wallet CLI with the daemon-login parameter, which should match the username/password that you set on the daemon.
So, the full command would be:
monero-wallet-cli --daemon-login monero_daemon_user:monero_daemon_pass --wallet-file /path/to/monero/wallet
Let the CLI sync the wallet (wallet sync is a separate process to the daemon sync). Then, proceed to start the monero-wallet-rpc service. This is the service that provides the API that the WordPress plugin uses.
Please let me know if you face any more issues.
with regards