I don’t think that would work for OP. Not only do they need it run-time, but also writing to the DT in BP is a no-no.
@ar_nobe You’ll need a plugin - either Rama’s Victory (comes in UE4/5 flavours) - you could parse the vector array to string, insert commas turning it into *.csv. You could then file IO save string array.
Or search the Marketplace for file ops plugin alternatives.