You have to use the Supermetrics' Connector.
After opening a blank report in Google Data Studio, click «Add data» and search for «Searchmetrics»
After clicking on «Searchmetrics by Supermetrics» you need to authorize Google Data Studio in order to use the community connector. Therefore click on "authorize" and "allow".
After you are done with GDS authorization process, you have to authorize with Searchmetrics in order to start pulling data. You'll need your API Key and API Secret.
You can find your API Keys in the Searchmetrics Suite > Settings > API Keys > Overview API Keys. If you haven't created one yet, read this article to learn how it works: API Management.
After you've filled in the fields, click on "start".
Select the «Query type» from the drop-down menu in order to start configuring your query. Go to the API documentation if you need explanation for the specific query types:
After selecting your query type, fill in your parameters and click «Add».
By adding the first data source, you get a table including basic information.
You can add more metrics to the chart just by dragging data fields to the «Metric» area.
You can add another chart to your visualization using the same data source by clicking on
«Add a chart» and select the chart that you want to add (e.g. a scorecard).
As you can see, the scorecard is directly added with the relevant information.
You can add another data source by clicking on «Add data» and select another query type
(e.g. Historic SEO Visibility).
Once again, fill in your parameters and click «Add».
If a chart does not show up automatically, you should add it manually by clicking on
«Add a chart».
Click, once again, on the chart that you want to add to your visualization
(e.g. a time series chart).
The chart would be automatically filled up with relevant information from the data source.
You can create more appealing charts by playing with the style of the chart.
With a little bit of rearranging and cosmetic changes, you now have your basic dashboard.