Closed captions offer many benefits over open captions, such as the ability to switch them off. However, in some circumstances you may want to burn subtitles into the video, for example for distribution on social networks. 

To do that, you will need to import the subtitle file into Premiere for burning.

Firstly, you need to export your subtitles from Flow. Go to the clip in question and open the Subtitle Editor. There, choose 'Export subtitles' and pick the STL format. 

Next, open Premiere and import the STL file like any other clip. Be sure to make a note of the video clip size. 

Convert the file to open captions by using control/right-click on the subtitle asset > Modify > Captions...

The next step is irreversible, so you might want to make a backup of this clip before proceeding. Once you've done that, change the standard to 'Open captions' and change the video settings so they match the video.

After that, we need to format the captions. Double click on the subtitles clip in the project panel. The captions panel will open. You can now use shift-select captions so that changes are applied to all subtitles or change individual blocks.

Then, we can reposition the subtitle timeline. In the timeline panel, create a marker at the same timecode. 

Position the subtitles clip at the first subtitle in marker.

The only thing left to do now is to export the subtitles. Ensure that you burn in the captions when doing so.