Installation with postgres

Hi:
I try to install prjeqtor. If I choose mysql the checkboxes of tool/configCheck.php will be shown. But I want to use postgres
If I choose postgres, there will be no error specious (click ok and nothing happens). The browser-inspector give me a 500 with the configCheck. url/tool/configCheck.php manual says:

PHP version is 7.3.14-1~deb10u1 : OK
Module PDO is available : OK
Module PDO for '' is not available - check your php configuration (php.ini)
[...]

I installed and activate pdo, so I have extension=pdo_pgsql and extension=pgsql in my php.ini.

My apache-error.log is confusing, because it sounds like a ssl-error. But in this case I should not see any page...:
[Wed Jun 24 13:50:01.789377 2020] [ssl:info] [pid 30392] [client 94.134.88.79:15473] AH01964: Connection to child 3 established (server projects.foo.org:443)
[Wed Jun 24 13:50:01.790325 2020] [ssl:debug] [pid 30392] ssl_engine_kernel.c(2319): [client 94.134.88.79:15473] AH02043: SSL virtual host for servername projeqtor.foo.org found
[Wed Jun 24 13:50:01.790350 2020] [core:debug] [pid 30392] protocol.c(2314): [client 94.134.88.79:15473] AH03155: select protocol from , choices=h2,http/1.1 for server projeqtor.foo.org
[Wed Jun 24 13:50:01.812869 2020] [ssl:debug] [pid 30392] ssl_engine_kernel.c(2235): [client 94.134.88.79:15473] AH02041: Protocol: TLSv1.3, Cipher: TLS_AES_128_GCM_SHA256 (128/128 bits)
[Wed Jun 24 13:50:01.813113 2020] [socache_shmcb:debug] [pid 30392] mod_socache_shmcb.c(495): AH00831: socache_shmcb_store (0xf4 -> subcache 20)
[Wed Jun 24 13:50:01.813143 2020] [socache_shmcb:debug] [pid 30392] mod_socache_shmcb.c(849): AH00847: insert happened at idx=0, data=(0:32)
[Wed Jun 24 13:50:01.813155 2020] [socache_shmcb:debug] [pid 30392] mod_socache_shmcb.c(854): AH00848: finished insert, subcache: idx_pos/idx_used=0/1, data_pos/data_used=0/212
[Wed Jun 24 13:50:01.813165 2020] [socache_shmcb:debug] [pid 30392] mod_socache_shmcb.c(516): AH00834: leaving socache_shmcb_store successfully
[Wed Jun 24 13:50:01.821515 2020] [ssl:debug] [pid 30392] ssl_engine_kernel.c(383): [client 94.134.88.79:15473] AH02034: Initial (No.1) HTTPS request received for child 3 (server projeqtor.foo.org:443)
[Wed Jun 24 13:50:01.821759 2020] [authz_core:debug] [pid 30392] mod_authz_core.c(820): [client 94.134.88.79:15473] AH01626: authorization result of Require all granted: granted
[Wed Jun 24 13:50:01.821781 2020] [authz_core:debug] [pid 30392] mod_authz_core.c(820): [client 94.134.88.79:15473] AH01626: authorization result of <RequireAny>: granted
[Wed Jun 24 13:50:01.823956 2020] [deflate:debug] [pid 30392] mod_deflate.c(856): [client 94.134.88.79:15473] AH01384: Zlib: Compressed 1207 to 341 : URL /tool/configCheck.php
[Wed Jun 24 13:50:06.829530 2020] [ssl:debug] [pid 30392] ssl_engine_io.c(1106): [client 94.134.88.79:15473] AH02001: Connection closed to child 3 with standard shutdown (server projeqtor.foo.org:443)

I have no ideas where I can keep on searching. Could anyone help me, please?