Hello; if I remember correctly, the generated D64 should be inside a "bin" subdirectory inside the project's directory.
57 days ago(+1)
I never find it. When i export my work there only 2 folder one for the back ground end the other for the portrait , a 2 file the code in .xml and a .json file. i know there a D64 created during the process but i think the program throw it directly to the emulator.
i check in every directory of the program. Maybe there is someting i miss. ?? 
56 days ago(+1)
I finaly found it, is in BlocklyVN8bit-0.3.0 /8bitunity/build
I dont know why i dont see it before ?? Thank you , i continue to work on it.
Thanks; now I see that it would be interesting if the tool had a button for easily downloading the generated binaries; I'll take a note so I don't forget:
https://github.com/haroldo-ok/BlocklyVN8bit/issues/56