This data source is depreciated with Grafana 6.5+

[cjslack]

Read me should be updated to include this info. Per Noa:

Users who have upgraded their version of Grafana to 6.5, can no longer work with our plugin (it is based on Grafana ES plugin and it was changed).
From Grafana 6.7 and above, Grafana added the same capability to their ES plugin, that means that they can use Grafana ES plugin to view their Logz.io logging account, they will need to do the same thing they did when installing our plugin, but they will need to do in the ES plugin
(https://grafana.com/grafana/plugins/logzio-datasource).
For versions between 6.5. to 6.7 we currently do not support, so users may upgrade to 6.7 or roll back a version.