Zoho Assist Self Client, help with connection

Zoho Assist Self Client, help with connection

Hello everyone!

I'm writing this post because I need help with connecting to zoho assist api.
I made a Self Client and I can't figure out what to do next.
My questions are:
1. Can I use Postman to test zoho assist api?
2. In the tab "Generate Code" in Self client, what do I use the generated code for?
3. When I make a call, I get an information: "Invalid redirect URL address", but in self client there is no field to input redirect URL address.
I know I'm doing something wrong, I just can't figure out what it is.
Example call (copy paste from postman): 
Do I need to add more parameters? (state, redirect_uri, access_type)?
If I do, what am I missing?

Thanks for help!

PS.
That is obviously not my client id.