Linking my FiveM server to my VPS

Hello,
I rented a vps from OVH to connect my server to the vps.
I have followed several tutorial, and when I run my server I have that errors.
Would you tell me what I should do?
Thank you very much.

https://image.noelshack.com/fichiers/2017/24/5/1497612065-error-yellows.png

What server ? What os ? Version of the server, of the os ? Of your mono installation

FiveM base server for the moment.
&
Linux Debian 8

Mono 5.0 Error, u have to install mono 4.8 manually to have your server ok

Or can I find this version of mono?
I need to uninstall 5.0 before installing 4.8?
Thanks