When activating the plugin I am getting the message
Wordfence could not get an API key from the Wordfence scanning servers when it activated. You can try to fix this by going to the Wordfence "options" page and hitting "Save Changes". This will cause Wordfence to retry fetching an API key for you. If you keep seeing this error it usually means your WordPress server can't connect to our scanning servers. You can try asking your WordPress host to allow your WordPress server to connect to noc1.wordfence.com.
When I hit "save options" I am getting the error message
Your options have been saved, but we encountered a problem. You left your API key blank, so we tried to get you a free API key from the Wordfence servers. However we encountered a problem fetching the free key: WordFence API error: Your site sent us an invalid Site URL when requesting an API key. We received: ''
Entering an API key I got from the wordfence.com didn't help either.
The site is hosted on a managed server. Any tips are appreciated.