If you received the error message 'Http request failure', you need to allow Http Client Requests in the extension settings for Xe Currency Data for Dynamics 365 Business Central. To do this: 

1. In the search bar in the top right-hand corner, type Extension and choose Installed Extensions
2. Search for the Xe Currency Data extension
3. Click on the link to Xe Currency Data for Dynamics 365 Business Central
4. In the Extension Settings screen toggle on Allow HttpClient Requests