Installation troubles on Ubuntu 16.04-18.x with xampp

1. Installed clean Ubuntu 16.0.4
2. Downloaded and installed XAMPP 7.2.26
3. Checked http://localhost - works good. Apache, Mysql and ProFTPD started.
4. Downloaded projeqtor 8.2.4
5. Unzipped and moved to /opt/lampp/htdocs
6. Opened http://localhost in browser
7. On the Configuration page click "OK"

Got several errors:
1. SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: YES) dsn = mysql:host=127.0.0.1;port=3306
How fixed: removed default DB rassword.
2. incorrect value for 'Log file name', cannot write to such a file : check access rig
How fixed: chmod 777 files/logs/
3. incorrect value for 'Parameter file name', cannot write to such a file : check access rights
How fixed: 1. created manually files/config/parameters.php 2. chmod 777 files/config/parameters.php
4. impossible to write \'../tool/parametersLocation.php\' file, cannot write to such a file : check access rights
How fixed: chmod 777 tool/
5. max_input_vars=1000 is too small - value should be at least 2000, 4000 recommended - check your php configuration (php.ini)
How fixed: added to /opt/lampp/etc/php.ini line: max_input_vars = 4000

All the erors are fixed. I see "On next page, log in as user "admin" with password "admin""
8. Click "Continue"
Now I have an error: SQL ERROR : Database type unknown

How to fix this?

Very strange because I see in XAMPP popup:
MySQL Database Running
ProFTPD Running
Apache Web Server Running

Where is the log-file located?

/opt/lampp/htdocs/files/logs/ has index.php only. Double-checked, logs directory has 777.