Hi @michiel. Thanks for your help. I tried to execute the bnsupport application on Windows but it fails.
However I solved in this way for those who are interested:
I changed the "X-Frame-Options" in the railtie.rb file (C:\Bitnami\redmine-4.0.4-5\ruby\lib\ruby\gems\2.5.0\gems\actionpack-5.2.3\lib\action_dispatch\railtie.rb and C:\Bitnami\redmine-4.0.4-5\apps\redmine\htdocs\vendor\bundle\ruby\2.5.0\gems\actionpack-5.2.3\lib\action_dispatch\railtie.rb). Instead of "SAMEORIGIN" I changed the value with "ALLOW-FROM https://xxxx.zzzz.com"
Then I added the line RequestHeader set X_FORWARDED_PROTO 'https' in the c:\Bitnami\redmine-4.0.04-5\apache2\conf\httpd.conf in order to redirect to https protocol each post request:
<IfVersion >= 2.4.7 >
Header always setifempty X-Frame-Options "ALLOW-FROM https://xxxx.zzzz.com/"
<IfVersion < 2.4.7 >
Header always merge X-Frame-Options "ALLOW-FROM https://xxxx.zzzz.com/"
RequestHeader unset Proxy
RequestHeader set X_FORWARDED_PROTO 'https'
Now I can open redmine application into iframe from my application