It doesn't? See Can you write code with android tablet - #10 by Kirill_Yamney and Can you write code with android tablet - #9 by Ken Possibly use a Puffin browser and tell us what happens.
No, it does not produce an apk. There are complex ways to transform Scratch to an apk does scratch produce an apk - Google Search
I wouldn't want to do that .
See https://scratch.mit.edu/ .