So I finally have a PC and have the capability to submit things to this website... spent several hours learning how to make all the necessary conversions of my Musescore files into Finale files... only to find out that it is literally, completely, legitimately impossible to meet the submission guidelines with only Finale Notepad. I don't have $600 to drop just so I can indent the first system and add measure numbers.
I'm quite frustrated, as I was really looking forward to submitting a few things, and I don't understand why a) Finale Notepad lacks such BASIC functionalities when software like Musescore has them available for free, b) the admins of this open-source, free site would decide that its volunteer submitters can only use the software that locks basic functionalities behind a paid gateway (and excludes Mac and Linux users as well).
I'm sorry if I come off as short here, but I'm annoyed and confused. This website has brought me a lot of joy and entertainment over the years, and I wanted to contribute to it, but I'm feeling pretty excluded here.
If you want to meet the submission formatting guidelines with Musescore and your only Finale product being Finale Notepad, definitely try out the template and program in
https://www.ninsheetmusic.org/forum/index.php?topic=10136.0. Copy your desired music into the template first, fiddle with the copyright, etc. ...Or just follow the instructions in the OP of that thread. Be aware that Step 5, "Drag-and-drop the .xml on the .exe", is Exactly As It Says On The Tin, and attempting to run the .exe won't work. Do whatever necessary to make the .exe pass virus checks. ...Then you'll have to move the "quarter note = # bpm" away from the "Allegro"-like tempo indication in the Finale file. And you'll likely have to adjust ottava lines and the notes they affect in the Finale file, too. But at least you should meet the submission formatting guidelines now!
I'm a fellow Musescore-into-Finale-Notepad user and Musescore fan myself, and the template and program in that thread have made submitting scores to NinSheetMusic substantially easier for me without paying a cent for music notation software.
...I don't trust whatever Musescore 3.0 tries to do with "smart-adjusting" the template and its contents, though, so I work on template-using music in Musescore 2.X only.
I've personally heard and read that this website primarily uses Finale for legacy reasons and because Finale is rather popular and changing primary file formats or adding additional ones is surprisingly hard in the back-end. I guess we haven't received enough complaints from Mac users (who apparently can only use the fullest-price Finale version) to make a file format change.
...I also personally doubt that NinSheetMusic itself is open-source. The times I've brought up a website-related bug report, I always got the hunch this website was closed-source.