Hi @Juanjo_Martin_Cara and welcome to the MongoDB Forums!

Just tried it on an AWS, free tier M0 cluster and I’m able to select my cluster. I just went through these two screens:

And then:

Can you try to create a new project in your organization, then create a new free cluster in a different cloud provider / region to find the root cause of the error?

Again, welcome to the MongoDB community and hope this helps!