bbPress.org

Hello guys, i’ve created a website on free hosting. Installed latest version of WP (4.8.1), installed some plugins, theme, everything works perfectly. But, when i installed bbPress 2.5.13, i saw that i wasn’t tested on this version of WB, but i tried. As result: when i go to mydoman.com/forums/ it shows me ERROR 500. Also, when i go in dashboard >> Forums >> List of Forums (maybe it’s named so, cuz i’m using russian version of WP) it also shows me ERROR 500.
I Decided to downgrade (reinstall) the entire WP without any plugin and theme. I choosed version 4.7.5 as it says that is tested on bbPress 2.5.13. So, i installed WP, installed bbPress, and tried to go to dashboard >> Forums >> List of Forums and it returns me this:

if image is too small, here’s the link to it: http://i.imgur.com/UPirh3p.png
Idk what to do and what to try.
Thanks for helping.