My website system(CMS) is not displayed

[Vialpando]

Hello,
I have some problem with my website(CMS). I uploaded the files from archive, also imported SQL in phpmyadmin and finally i edited the database.php file in ftp. Actually the problem is that my website is not displayed - i filled all my data true - just a white screen, showed none errors.

PhpBB version: 3.3.1(the newest)
PHP Version: 7.4.x or 7.0 default I guess

Link: http://attach-bg.rf.gd/

I will be extremely grateful if you help me, because I intend to use the system in the future.
Thanks in advance!

[XInterverse]

I get a HTTP ERROR 500. Click and read the article below:

Http error 500