The package you reference are the ones using the Elastic license and not the ones using the OSS license. Basically your using the default distribution of elasticsearch and filebeat and not the OSS distribution. If your not familiar with all that you should check the subscription page to understand the differences. I don’t think your issue is related to any of that, and once you understand the licenses you’ll probably use exactly the packages you’re using now.
Now your error indicate your elasticsearch cluster (or single node cluster) has not formed correctly. ES might be running but there is more to it than that. It also needs to form a valid “cluster”, even if its a single node. That because there needs to be a master.
It doesn’t appear you have read the doc/release notes/breaking changes for version 7 since you say you kept your config the same. That’s not going to work. Hence the error about not discovering a master.
I recommend reading the logs of your ES node which you haven’t shared here, instead of the filebeat logs. Also the install docs for es 7, with the breaking changes too. You’ll see there are new settings required to start a 7.x ES. I’m thinking those required settings are not in your conf, which you haven’t shared here.
You’ll be on the right path I think.
As for the filebeat error message, I currently think this is a misleading error message because filebeat thinks your mixing OSS ES with Elastic license filebeat. I think filebeat is confused because it cannot call the license endpoint, but in this case the reason why it can’t is because your ES is not healthy and has not formed a working and valid ES cluster.