To install the Kilomail on an app you would first need to download the app from either the App Store or Play Store, Just search for Nextcloud or use the below links:
Once you have downloaded and installed the app you need the following settings:
Server address: https://kilomail.co.uk/nextcloud
Username: This is your portal username or your kilomail username if external
Password: This is your password to access Kilomail or the one you use to access the nextcloud site if external.
Once this is set up you should be able to access the cloud on your phone.