This is a web app and is therefore not downloaded to your phone. You can put a shortcut (icon) on your iPhone, iPad, Android tab, etc. then the web app functions exactly the same as an installed app.
See here how:
For iPhone with Safari:
Look for the share icon at the bottom of your iPhone
Scroll down and then click on:
'Put on home screen'
Click on 'add'
Ready! From now on you can open this web app by clicking on the placed icon​
For Android with Chrome
Click menu settings in the top right
Click on 'Add to home screen'
Click on 'add'
Ready! From now on you can open this web app by clicking on the placed icon