Fix the timing
Sometimes, the BPM is wrong and the notes aren't perfectly sync (the eventually issues are from the files, I can't do anything from that). To fix that, we will use the osu! editor.
This happens especially if you didn't checked 'Unique BPM' option when you could use it... It's possible to have duplicate BPM too (like you have 25 times the timing point 190 BPM)
In the example above I have 100 BPM and 210 BPM.
To know what is the good one, either you go on the internet to get the BPM ; or go the timing section and use the sounds to find which one is good.
For the example the BPM is the same. I heard that 210 BPM fits way more that 100 BPM.
Once you have the good BPM, open the timing setup panel. In the list, you will find the good BPM (BPM are red dotted lines). If it's not the first line, copy the good BPM value to the first line. Copy the multiplier below the good BPM you found too (for the scrolling speed), and copy it to the 2nd line (it should have the same time than the first line).
Then delete the other line to keep only the 2 firsts.
Doing the step above may leads to an invalid offset, the metronome isn't sync with the song.
To fix that, go to the beginning of the song, play it, and stop it* when you heard a beat of the song*.
Then open the timing setup panel again, select the 1st line, and change the offset to the time of the 1st beat. Apply this value to the 2nd line too.
If you need to adjust, you can use the Offset value. Be sure you unchecked 'Move already placed notes when changing the offset/BPM' before doing that.
Verify again the BPM by using the metronome and the song. Go at random parts of the song. If the song and the metronome are usync, the BPM is wrong (or you are very unlucky).
To fix that, check 'Move already placed notes when changing the offset/BPM' and adjust the BPM using arrows until it's okay. Avoid very precise value like "214.494". Try to get an integer first, then only 1 decimal, and eventually a very precise value (it's extremely rare).
If you did the things correclty, you can see that the notes are perfectly aligned with the colored line (if sometime not, try with the beat snap divisor 1/3).
For Ballistic, the BPM is 210.5
Finally, press [Ctrl]+[S] to save changes.