Firstly, you have the advantage of Belgian blood. Eddie Merckx would just say: ride your bike and then ride it some more. But seriously, I’d highly recommend two things:
Make yourself knowledgeable on how to train for cycling fitness. There are some great books on the subject with training plans. Joe Friel’s “The Cyclist’s Training Bible” is a great book to start with. Basically, you don’t need anything more. Which brings me to my second point:
Keep it simple. Don’t get too fancy with all the Zwift workouts. They are basically tricking you with over-complex training. Watch this video from a very good coach and an outstanding racer, Dylan Johnson on YouTube. He has a video about why Zwift training programs are too complex.
After finding your FTP using the 95% of 20 minute all out effort, my recommendations to you are to do three types of exercises:
Sweet Spot Training: This is one hour of riding done twice a week. Do a 10 minute warm up. Just spin and do some spin ups to 110 rpm or so and hold for 30s to a minute and then back off. Do 3-4 spin ups in your 10 min warm up. Then do 2 intervals of 20 minutes each at 85% of your FTP. Don’t cheat by going too hard in the beginning. Just pace it nicely. You should see your heart rate rise towards the end of the 20 mins and it will feel hard but not killer hard. That’s the idea of ‘sweet spot’. Then rest for 10 mins spinning at 50% of your FTP. Then do another 20 min effort like the first one and cool down for 10 mins. Very simple. But highly effective. This will help raise your FTP. Twice a week.
VO2 Max intervals: These are the most important if you are going to race. The reason a rider gets dropped is because they are being asked to ride above FTP. Most people cannot ride above FTP for more than 5-8 mins. This is your VO2Max zone. You need to train it. It’s super important. You need to do only 2 sessions per week. Very simple but very hard to complete. But I guarantee you that after 6-8 weeks of these, you will be a beast on the bike! OK, they go like this: Do the warm up. Make sure to really get several visits to 110-120% of FTP during the spin ups. Your legs need to be primed. Then start with a 3 minute effort at 110% of FTP. Then rest for 3 mins at 50% of FTP. Then do another. Do 7 x 3 min 110% of FTP. When you get good at these, you can try to increase to 115% and so on. Make sure you are nicely rested the day before so that you get GOOD QUALITY TIME at VO2Max. So don’t go racing or thrashing it the day before. Do not do more than 2 sessions per week. Again, see Dylan Johnson for the science on this.
The other days, just ride very easy or freely. Part of cycling is developing efficiency. This means that your brain needs to be trained to fire the muscles in specific order to become more efficient. The only way to train your neuromuscular system is to spin your legs. You just need to spin. It doesn’t matter what power. So on your ‘off days’, just ride for the enjoyment of it. Try not to take your heart rate up too high. You want to fee fresh for racing or interval sessions.
You can replace a 2x20 session with a 40 min+ race (because it will likely be at your FTP) or try riding up Alp du Zwift at 85% of your FTP. I do that a bit to mix things up.
Another great 2x20 (actually 2x25) ride is the Innsbruckring UCI course. You can go up that hill twice and then cool down and you are done with your workout. It’s perfect.
But the biggest secret to making gains is consistency. If you consistently ride your bike and do not miss, you will see great gains after 3 months. If you do the simple workouts I mention above twice a week, then you will improve. Guaranteed. Recheck your FTP every 6 weeks and recalibrate your workouts.
ENJOY GETTING STRONGER! All the best.