In recent versions of Airwave you can create an sftp user via the Advanced menu:
Advanced
1 Restart Application
2 Reboot System
3 Configure Network Settings
4 Set Hostname
5 Set Timezone
6 Shutdown System (halt)
7 Add File Transfer User
b >> Back
Your choice: 7
Running Add File Transfer User
When entering the username it must have 5 or more characters
and contain only lowercase letters or numbers.
Username for the File Transfer User (default 'awsftp'):
When entering the password you must follow these rules:
Minimum 8 chars with upper, lower, numeric, and non-alphanumeric characters.
Spaces are not allowed.
Password for 'awsftp':
Creating File Transfer User 'awsftp'
Changing password for user awsftp.
passwd: all authentication tokens updated successfully.
Reloading sshd: [ OK ]
You may now sftp into your AMP with this user.
Due to security concerns this user will be removed each night.
File transfers take place in the user/ directory.
Press Enter to return to the menu ...
After that, you can sftp into the Airwave server:
ubuntu % sftp awsftp@airwave
awsftp@airwave's password:
Connected to airwave.
sftp> ls
file_transfer_from_the_user_directory user
sftp> ls user
user/ampbackup_2018-08-14_17-16-23.tar.gz user/awsupport.gpg
user/nightly_data001.digest user/nightly_data001.tar.gz
user/nightly_data002.digest user/nightly_data002.tar.gz
user/nightly_data003.digest user/nightly_data003.tar.gz
user/nightly_data004.digest user/nightly_data004.tar.gz
user/pre-upgrade-8.2.6-data.tar.gz user/pre-upgrade-8.2.6.1-data.tar.gz
If the feature isn't there, you might need to upgrade. It's available at least in Airwave 8.2.7 (and I believe in 8.2.6 as well).