Downloading Schematics

Ok, here I'm using MCEdit 2 (64bit) ver beta 14 (113) and I've imported the schematic you've given me the link for above by starting MCEdit, then choosing a random 1.12.2 map, then choosing the edit option for the map, clicking on 'Import / Export at the top of MCEdit, then on the drop-down menu, clicking 'Import, navigating to the 'providenceclass-1531699707.schematic' file and accepting it.

Here is a picture of the import into this random 1.12.2 map :

https://www.dropbox.com/s/zo1d644u8sqp8h5/shipschematic.png?dl=0

So, knowing how to do it, and knowing that it works, the only other issue is that you might be trying to import your scematics into a map higher than 1.12.2, which won't work since MCEdit 2 currently doesn't support maps higher than 1.12.2, or perhaps you are trying something different than the above procedure.

Just to go through it again, open up MCEdit, click on the 'choose' button over to the left and navigate to the map folder you wish to import the scematic into. Once chosen, click on the 'EDIT' button near the bottom of MCEdit to open the map in edit mode, then click on 'Import / Export' and from the dropdown menu, choose 'Import' option - this dropdown can be seen in the below picture link :

https://www.dropbox.com/s/ptsku9pjtj9woom/mceditimport.png?dl=0

when you click on 'import', navigate to where you have the schematic file stored and double-click it to import it. Hopefully you will have similar success to myself.


[​Edit]
In case you are trying to double-click on the downloaded schematic file without first opening a map in MCEdit, then, if using Windows, you will just receive an error similar to the one you describe, as Windows has no idea what program to use to open a schematic file with.