Hi. As far as I’m aware, there are no rules on AJ regarding public domain works. You don’t even have to credit the original composer if you don’t think it will be a benefit. Technically, you could even rename the track “Motivational Inspirational” if it fit that theme. If you have made your own arrangement of it, you can also register it with your P.R.O. and claim 100% writer royalties as the arranger.
Only thing to bear in mind is that some compositions which are in the public domain have popular arrangements which are copyrighted. Orchestral pieces which have been arranged for piano by contemporary artists for example.