@AdrianMake - These posts/messages were before the Make team added the ability to ‘Bulk Add Rows’ natively in the Google Sheets App. So now there is no need to do it manually as discussed in this thread/showcase.
Just note that using the Make built in Bulk Add Rows module does require the use of aggregators and it’s a bit tricky using it the first time, but once you get it working it will ‘click’.
@samliew shared some helpful info in this post:
To answer your question about how to ‘copy/paste’ the code - you just need to copy the JSON from the first post and in an open Make scenario (one that is in the ‘edit’ mode) - you just ‘paste’ the JSON directly and Make will convert it to the 3 modules.
I hope this helps!