Installation issue: Database unavailable error message

Hi, I see in the forum that I am not the only one with this issue but I can’t figure out what’s wrong from the other threads. I have little background in this but I came so far:

Ubuntu 16.04 LTS
Server version: Apache/2.4.18 (Ubuntu)
PHP Version 5.6.25-2+deb.sury.org~xenial+1
SuiteCRM 7.7.4

  • I can run php-scripts in my browser
  • I can open mysql with [color=#ff0000] mysql -u root -p[/color] in the ubuntu terminal
  • I added [color=#ff0000] extension=mysql.so[/color] in php.ini

But still I am stuck on the following error message:
[color=#ff0000]
Database unavailable

Database Support was not found. Please make sure you have the necessary drivers for one of the following supported Database Types: MySQL or MS SQLServer. You might need to uncomment the extension in the php.ini file, or recompile with the right binary file, depending on your version of PHP. Please refer to your PHP Manual for more information on how to enable Database Support.

XML Parsing

Functions associated with XML Parser Libraries that are needed by the SuiteCRM application were not found. You might need to uncomment the extension in the php.ini file, or recompile with the right binary file, depending on your version of PHP. Please refer to your PHP Manual for more information.

MB Strings Module

Functions associated with the Multibyte Strings PHP extension (mbstring) that are needed by the SuiteCRM application were not found.

Generally, the mbstring module is not enabled by default in PHP and must be activated with --enable-mbstring when the PHP binary is built. Please refer to your PHP Manual for more information on how to enable mbstring support.

Writable Cache Sub-Directories

The files or directories listed below are not writeable or are missing and cannot be created. Depending on your Operating System, correcting this may require you to change permissions on the files or parent directory (chmod 755), or to right click on the parent directory and uncheck the ‘read only’ option and apply it to all subfolders.[/color]

Thanks in advance for any tipps/ideas.