Moving Bludit to new domain

[alex611]

I have read all posts regarding 'moving Bludit to new domain'
Everywhere there is this 'domain migrator' tool mentioned.
There is NO documentation how to do that manually.

Not because of the money, but because (obviously) some people would like to know how this is done manually, which files to consider etc.
That would help to understand the CMS better.

The domain migrator tool, all it does is to enter a new value into /databases/site.php and to search/replace URL's in pages .txt's.
Yes, it also clones the bl-content structure

I downloaded the plugin and since it is 3 years old, i was afraid, it won't work.
And it doesn't.
I followed instructions here:
https://docs.bludit.com/en/bludit-pro/domain-migrator
After clean install of Bludit, and after uploading the bl-content (from migrator) the install.php kicks in again and asks for re-intallation... which fails.

Searching again for solution, i came across this post
viewtopic.php?p=5612#p5612
It only says: Download Bludit v3.0
So one could assume that the installation should be after migrating the content.

Now i am more confused than before

A few questions though:

a) why the standard recommendation is 'make fresh install' of Bludit, instead moving the whole existing app to new domain (and adjust files necessary)? What's the catch?

b) Why is there no concrete and clear documentation about migration process and files which need adjustment?

c) what do i do now, to debug, since the migration (with the plugin) failed?