Google analytics custom dimensions into data studio

I'm looking at tracking custom dimensions that have been set up in google analytics within data studio.

I can find the custom dimensions that in analytics but I cannot find how to get them in data studio unlike the other metrics.

These dimensions are tags coming from drupal. An issue I have with this is that tags are coming in with commas in them. Two separate tags Topic1 and Topic2 would be able to be 3 different tags as it currently is:

Topic1

Topic2

Topic1, Topic2

I want to be able to track these topics individually so the 3rd row here (Topic1, Topic2) would add a count toward both Topic1 and Topic2 separately.

Question Summary How to get custom dimensions into data studio reports?

How to track comma separated values in these reports?

All suggestions will be appreciated.