Please send to us Wave files 24 (or 32) bit with headroom about - 6db per channel separately, like: KICK, BASS MID, BASS SUB, CLAP HI, CLAP MID, CLOSE HATS, OPEN HATS, PLUCKS, LEAD1, LEAD2, PAD1, PAD2, etc.
Note: you can group similar instruments or audio files like: FX, HATS, CLAPS, PADS, etc. in one channel, to decrease number of stems
You can check
this video if you are not completely sure what to do: