BTW if you are a Portuguese citizen you can register your company in a easier way, from this page: https://e-estonia.com/component/e-business-register/
Finally if you want to open a company in estonia you will need a physical address, fortunately the government is aware of this hurdle, and in it's website suggest an handful of providers: https://e-residency.zendesk.com/hc/en-us/articles/205207022-...
The one with the nicer website is LeapIN, that has very affordable prices...