The most important thing to do is master your basics. So, for example, if you can't hold a 1 minute single stroke roll at 150bpm with your hands and feet, then this is something you'll need to work on.
Get yourself a good Double Bass Drumming book - I recommend The Encyclopedia of Double Bass Drumming and/or Virgil Donati's Double Bass Freedom. I have both. The Encyclopedia is what I used when I was first learning double bass and it was a tremendous help but Virgil's book (which didn't exist back then) should be just as useful to beginners.
A lot of prog utilises odd-time signatures as guys have stated. The best thing you can do to become accustomed to playing these is simply to expose yourself to the music and try to count it. Eventually it becomes instinctive to play in signatures such as 7/4, 7/8 and even 19/16 is not as hard as it sounds.
Don't try to emulate exactly what guys like Matt Garska are doing straight off the bat. Remember what I said about mastering the basics? You need to understand the patterns and concepts that these guys are applying. They're not necessarily thinking in terms of individual notes, more likely they're thinking in groupings of notes, or phrases. You may hear a linear pattern which sounds like a blur of notes, but to them it's just a grouping of for example RLrrllBB.
For these sorts of linear patterns I can highly recommend getting Sticking Patterns by Gary Chaffee - and have a look on Youtube for ideas on linear patterns to see how they can be applied.
The first prog song I ever learned was Pyramids on Mars by on the Virg. I only had about 3 years experience at the time and the main groove has a kick drum polyrhythm played in a 7/4 feel. It was hard work to listen to it and learn it at the time but it was the gateway for me and totally changed everything. Sometimes it's good to just throw yourself in the deep end.
But definitely start trying to play along with some easier prog songs, e.g., Overture 1928 by Dream Theater. Never stop counting while you're listening and learning, especially in periods of silence or pauses that may throw off your count.
Lastly, the main thing to remember with guys in these bands is that they spend a LOT of time playing and experimenting. Don't be daunted by however many years of experience they have compared to yourself - consider their experience a gift for you to learn from! Don't be one of those guys who watches a great solo and says "Gee I want to quit drumming now!" Get out the pencil and manuscript paper and write down some ideas in odd-time signatures. Get yourself a copy of MuseScore and learn how to use it to notate ideas. Try to start transcribing music as that will help you listen to music more easily and learn faster.