_MACANUDO

It ain't really enable NAT. It's "Port Forward". 
Project Paradise doesn't have the same power that the original TDU servers had, after all, it is a free to play online server. Original TDU servers could do it by themselves, but with Project Paradise you gotta do it yourself. 
Access your router via a web browser, and check for port forwarding.  Forward the port 8889, in both protocols, UDP and TCP. For that you might need your local ip address, which you can find out by opening cmd.exe and typing: "ipconfig". 
No, only through that counter. 

thanks for the necessary support, could you tell me if I would have to enable NAT on my router too? because the other players are marked in red and with a lot of lag for me, even though I know that the lag is in my connection

Not really no. Other than cheat engine, or profile manipulation, that's how you unlock all the roads. 
 
Although, if your problem is sorted, it is all good. 
Port forward in your router. Foward the port number 8889, both protocols. 
 
Also, give it a time to comnect, TDU is an old game, and connection takes a while to be stablished.  Plus, each session can hold 8 players, if it happens that you're the 9th, you will be set in a new session. 

apparently you were wrong, now I have everything unlocked and I still play online ^^