USE https://forkphorus.github.io/#546985155 . To get midi hex string, use https://tomeko.net/online_tools/file_to_hex.php?lang=en . Turn off 'Insert newlines after each 16B' and 'Use 0x and comma as separator', those are not needed. Same functionality as the original, but its been ported to work on scratch 3, since the original has broken. press "i" to import the midi hex text. Pasted HEX format should RAW string format, no separator. Then, press [space] and the file should be played using only internal noteblocks, no external sounds are used.
The midi hex importer was mainly the only thing i kept from the original (with a lot of modifications), rest of the scripts were replaced since they couldn't be recovered Default midi is from https://youtu.be/1cNkA3SO-HM