@Alex Efa   - I recommend that you take a look at using the Embedded Git open source package, which makes the power of Git available from within an IRIS instance (rather than using it client side which has shortcomings when it comes to things controlled in the SMP like Interop).  

This article may be of interest: https://community.intersystems.com/post/new-and-upcoming-embedded-git-fe...

Here is a helpful branching discussion on options for Embedded Git in our Health Connect Cloud product (the concepts would apply to any application of Embedded Git): https://github.com/intersystems/git-source-control/blob/main/docs/hcc.md.  You will see that it is quite common for developers to work in their own Namespaces on feature branches and then merge them in.  But this is only one of many models.

@Timothy Leavitt, @Pravin Barton  and @Nick Petrocelli can answer specific questions that you may have.
 

One possibility is that you don't have the appropriate Service enabled to allow for this connection.  This is pretty easy to check, from the SMP go to:
System Administration > Security > Auditing

If auditing isn't enabled then Enable it and run your test again, then go into View Audit Database and see if there is an access error logged.

It is quite possible that you don't have the Call-in service enabled (I don't think it is by default in Normal or Locked Down instances).  From the first .Net documentation link you provided:

[quote]

If InterSystems IRIS has been installed with security option 2, open the Management Portal and go to System Administration > Security > Services, select %Service_CallIn, and make sure the Service Enabled box is checked. If you installed InterSystems IRIS with security option 1 (minimal) it should already be checked.

[/quote]

Check that out and report back if it solved your issue.