See and connect to all available Sharepoint sites

[MH_Ger]

Background: In our company we use an an App for Teams which constantly creates new Sharepoint sites with unpredictable site names. On all of these Sharepoint sites will be Excel files with data that we want to append/combine. The problem is that, as far as I know, I can only ever connect to a single Sharepoint site (assuming that I know its name): 

= SharePoint.Contents("https://[companyname].sharepoint.com/sites/[sitename]", [ApiVersion = 15])

I was hoping, though, that I would be able to see all existing sites using the following command:

= SharePoint.Contents("https://[companyname].sharepoint.com/sites/", [ApiVersion = 15])

This however produces the following error:

I have a little more success with this command:

= SharePoint.Contents("https://[companyname].sharepoint.com/", [ApiVersion = 15])

It generates this list, which sadly contains no information about sites:

Maybe I need to have some Admin rights (which I currently don't possess) to see the sites?

Or is my code simply not adequate for the task? Or can it simply not be done?

Help would be greatly appreciated! Best regards!