How to create segmented reports by arbitrary custom variables or custom dimensions?

General questions
1

Suppose I have 100 clients and a thousand users of these clients who access my website. Is there a way to run custom segmented reports, based on say, clientID? If it is possible, what should I look into? custom variables or custom dimensions?

2

Hi,

Custom Variables and Custom Dimensions are nearly the same, but the latter are the more modern aproach and the one that is recommended to be used.

https://matomo.org/faq/general/faq_21117/

3

I did try custom dimensions and created a new segment. I am not sure how to create a report that group the data by the custom dimension, which in my case is Client ID. Is there a way to do it?