1. Manual install with Application Reference = softaculous_ref.
2. Check and move public/app/default/assets folder from manual to zip.
3. Check and move public/app/softaculous_ref folder from manual to zip.
4. Check and move storage/streams/softaculous_ref folder from manual to zip.
5. Exclude the following files while moving the above folders from manual to zip :
 public/app/default/assets/admin/theme.css
 public/app/softaculous_ref/assets/admin/theme.css
 public/app/softaculous_ref/assets/public/theme.css
 storage/streams/softaculous_ref/search/zend/default/{All .cfs, .sti and .del files}
6. Remove the following entry from composer.json
anomaly/installer-module
This is to disable the warning that the installer still exists.

Guide to install Composer :
https://getcomposer.org/doc/00-intro.md

curl -sS https://getcomposer.org/installer | php

php composer.phar install
7. Update from 2.2.x is not possible as confirmed by vendor via email.