Normally the provided License key works well on majority of servers. If this is the first time installation and having problem then in this case, you need to contact your hosting support providers. Some servers blocks API with GET request while trying to authenticate and validate the user API Key.
If you have used key before on any installation or either on demo server then same key won’t work for other multiple domain since it is valid for single domain only. Try deactivating before you use it in actual domain.