I submitted the following application but, it got rejected for UI.
Please help me…
It would be helpful if you’d post some screenshots. You’d get faster feedback 
Many people (including me) do not install .apk apps from untrusted sources, like private spaces on Google Drive.
Can you please suggest? And, splash screen is animated that’s why I didn’t give that. 
It’s not a category I know well but the typography doesn’t look great, the colours are a bit much and the icons all seem oversize.
That aside if you don’t have a working version in one of the stores, and are relying on the apk file, then I am not entirely sure the item will be reviewed properly