You can and should play these on any one drum, or move them around the drums. Play them at an even volume, or add accents. Rushing during fills is a universal bad thing lots of drummers do, so play with a metronome and practice 1) not rushing, and 2) not feeling physically tempted to rush— you know the feeling I’m talking about.
Per the instructions on the page, you should practice:
1. Ending the fill with a bass drum and cymbal on 1.
2. Playing the first note of the fill on the drums, or on a cymbal, together with the bass drum.
3. Make a two-measure phrase, filling at the end, crashing on 1, resting during the middle of the phrase.
4. Two-measure phrase, playing a rock groove of your choice for the first six beats, playing the fill on the last two beats.
You don’t need to exhaustively run through every possibility— just run these until you’re able to improvise your own fills along similar lines.