I have just downloaded Adobe XD and I have started to make my first few UIs there. I’ve been learning UIs for some time now, so I hope this is fine!
The UIs on the picture below are different UIs. We have the currency, admin call, Twitter codes, and a message notification. They are not meant to be added into the game together; just a practice. If possible, could you give me some feedback so I can improve? 
Round the Green and Red buttons a little bit and make them a bit smaller. Other than that, it looks great 
everything here looks good but, My suggestion is that you should ad A color wheel if the user of the UI does not like the color but anything but that it looks great!
Hey! I don’t really get what you mean, but there isn’t any user of the UI btw, it’s my practice UIs.
my bad… 
I’ll try to explain to you what happeneds if a person sees you UI and they don’t like the color of it and there no possible way to change the color and that why I recommended a color wheel. Did that work?
Oh! I can edit the colour on Adobe XD if they want.
Okay, that will works too, goodbye. 
Look nice for your firsts UIs
The only issue I see here is the UX. Avoid using the brightest green on the colour wheel with a plain white foreground, my eyes are diverted away from those buttons as soon as I look at them.
UX is a very important aspect of interfaces, there are alot of articles and tools that you can use to learn it.
Running your foreground/background colours through an online contrast checker is also helpful.
https://webaim.org/resources/contrastchecker/
Noted with thanks! I’ll definitely keep that in mind.