Librebooking install problems

[Dwokfur]

I was a phpscheduleit user some 20 years ago, I stopped using the application around 2016 and now I have to resurrect a schedule.
I tried to upgrade the old instance without luck, so I'm trying a clean install. New database, new user. The create-schema doesn't match create-data, because the layout has 3 fields in data, while the schema has only two. It was an easy fix. Now I try to browse to the Web/install directory and I see these in the logs:
Nov 9 23:10:13 hostname php: PHP Warning: Undefined array key "librebooking" in /var/www/localhost/htdocs/szivmr/lib/Config/Configuration.php on line 170
Nov 9 23:10:13 hostname php: PHP Fatal error: Uncaught Error: Call to a member function GetKey() on null in /var/www/localhost/htdocs/szivmr/lib/Config/Configuration.php:209
Nov 9 23:10:13 hostname php: Stack trace:
Nov 9 23:10:13 hostname php: #0 /var/www/localhost/htdocs/szivmr/lib/Common/Logging/Log.php(106): Configuration->GetKey()
Nov 9 23:10:13 hostname php: #1 /var/www/localhost/htdocs/szivmr/lib/Common/Logging/ExceptionHandler.php(19): Log::Error()
Nov 9 23:10:13 hostname php: #2 [internal function]: ExceptionHandler::Handle()
Nov 9 23:10:13 hostname php: #3 {main}
Nov 9 23:10:13 hostname php: thrown in /var/www/localhost/htdocs/szivmr/lib/Config/Configuration.php on line 209

Are there any ideas what is the problem here???