First of all i made the Wiki page Hacking:Building that contains a lot useful information.
But i also want to comment information you gave me.
If you want to build an installer for the develop branch you need to install Inno Setup.
When you clone you have all repository not just one branch. This is the reason why i do not recommend such a way for newbies. Probably you did not know that by default you will get the default branch. Before building you should switch to the develop branch.
Have you tried these two commands from the command window?
Cange to your Valentina clone directory first.
These commands pull the latest code from the bitbucket repo and switch your “view” to the correct branch:
I run these commands daily.