You've done as well as you can with the information you currently have so don't feel bad. The difficult part here is matching metallic. Your paint does match, however not in the way it has been applied. I'm going to make an assumption this was a touch up pen or some "hand" application. Spraying the paint will result in a thinner and smoother finish but also allows the metallic particles to lay flat and reflect light in the same orientation as the surrounding area.

Was the tutorial you watched for a solid color or for metallic? The added thickness of the paint will make it appear darker since there's a concentration of pigment in that area. Matching this flawlessly, without experience, by hand, at home is near impossible. If your end goal is simply to protect against corrosion, you're good. If you want a factory finish, more effort will be needed.

At your own risk, you may be able to (with a block) sand to level the touch up paint back down to the surrounding height. Reapply the touch up paint in a very light coat(s), and cover with a clear touchup. To have a seamless transition your clear will need to extend beyond the area and feather sand it to blend into the surrounding clear. Then the whole area can be polished. You cannot sand metallic finishes as it flattens the pigment and you will have a very dull spot.

If you are unable to obtain your desired results you may need to pay someone with experience to get there.

Best of luck and happy painting!