How to show the value of the service to users?

Question

User interface

I'm working on a concept for a social network for colleagues where they decide where to go for lunch.
The idea was tested in wireframes, many respondents became interested.
The concept has a list of restaurants, each with an invite button. Clicking on it generates a link for colleagues to have lunch.

When the user tests were carried out (3 people), everyone understood everything.
But after a "light" launch, an unsightly detail was revealed: no one clicks on Invite. Some users said they didn't know how. The problem seems to be that users are accustomed to social. networks already have some friends. And if there is no one, but there is no reason to call.
Now the actual question is: How to show the value of the service? That after inviting colleagues, it will be possible to choose with whom to go. We are currently working on an introductory page - onboarding - before loading the main one, but in my experience this does not always work smoothly, many do not read even very short texts.
Thanks for the advice.

Answer 1

Is there any value? What problem are you solving? Is this problem relevant? What solutions are currently available?
Start with these moments.

Answer 2

Let's start with the fact that I also did not understand anything. Which colleagues? Who is it for?

Answer 3

In fact, it’s already quite a sore point and one of the options for attracting users is motivation with money.
But the legends say that you need to tell how the user can improve himself or his life. Where he can get to arrive in one form or another and save something (money/time).
As an option, you can make partners among food outlets, they give a discount to users in exchange for new visitors.