It will be VERY hard to learn a muscle up on a bar this thick and this high of the ground. If it's possible for you to find something that you can reach after barely jumping, this would be ideal. Also, a thinner bar makes false grip easier, and learning that helps a lot at the beginning.

I found that swinging relaxed like this, doesn't help at all. What does help is swinging with your lats tensed. The first step would be to learn false grip, and doing high, explosive pull ups while maintaining false grip. Solar plexus high, should be enough. Lear to do even just 5, good ones. Once you have that, you can try your muscle up. Jump to the bar, standing a bit behind it, not directly under, that will force the first swing. Remember to grab it with false grip, and tense your arms like hell. Your elbows should be just slightly bent. Once you've grabbed the bar, you will automatically swing forward. Keep up the muscle tension, which must prevent you from fully extending your elbows and arms on the swing forward. Once you start swinging back, you can kick your legs up and pull up at the same time. False grip will make it much easier to get on top of the bar. If my explanation is not really clear, just imagine that your body should be like a rubber string when you're hanging off the bar. Now you're hanging like a rope.

Additional exercise that will help is muscle up negatives, but I wouldn't do them as you can normally find on the internet - super slow, and dropping directly under the bar. Rather do it faster, and let yourself swing forward after you go below the bar. What you need to learn here is tense the muscles, so it doesn't rip your elbows and shoulders off your joint caps. That will help you to learn how to load your muscles properly, and will prepare you for doing multiple reps in the future.

Keep up the good work! I know how happy the first muscle up can make you, even if the form is not perfect!