Problem when I want to authenticate my shiny application in a non interactive way

Hello,

I need to publish shiny applications on Rstudio Connect that will access the contents of GCP buckets.
To do so, I need to authenticate the shiny application so that it can access the bucket, in a non-interactive way.

For that I tried to create a service account for this shiny application, but when I create the JSON key it doesn't work.
I then talked about this problem to my team leader and he explained that this was a normal behavior. The company blocks the creation of these JSONs for security reasons.

As an alternative to my problem, I was advised to use the account service of the Rsudio Connect VM in my script to successfully authenticate myself.

But I have no idea how to do this.
Can you please help me ?