Need your opinion about GITLab-CI

Hello guys,

I am working in a lab where we develop, sell, diffuse and support softwares.
We need to share last versions of our apps internally (I mean the lab), and externally with partners and customers.
Moreover as we develop a lot, we have a non regression platform to do some tests.
These tests can be huge as we are working in the industrial CFD field.

We d like to be able to send softwares to others, and develop and trigger auto testing via gitlab ci, but using one unique platform for all these auctions. Is it possible ?

I want to avoid typical users running tests on the git lab server machine, but I want developers can do it.
Is there a way to do it?
Do you think it is better to have two machines ? like one with only gitlab, and another one, replicating the previous one but with gitlabCI and running non regression on it?

Thank you for your answers !!

Gregory H.