To edit Blackmagic Pocket 6K footage on an older computer it appears there may be a few strategies.
Strategy 1) HD Proxies
Convert the 6K footage in to HD proxies (as you would with RED camera footage) using programs like Adobe Media Encoder or Resolve.
Here is a video that discusses the subject:
Strategy 2) Use Blackmagic RAW 1.6 Update to Edit 6K BRAW Files Straight In CC
This video discusses the 1.5 update because it is a year old and that was the one available at the time but the information is good on how to handle the 6K right in Premiere CC 2018.