If you do not have Estonian digital identity card, Mobile-ID or Smart-ID, you can register a company by physically visiting a notary in Estonia. Here is the list of all Estonian notaries. All notaries charges the same amount of money for company formations as the prices are regulated.
If you cannot visit Estonia you have an alternative of preparing and certifying a power of attorney. It is a document that specifies who can represent you in Estonian notary and for what purpose. It will be a very detailed document to include your exact intention as a founder. If it is not in Estonian or English then probably it needs to be be translated too by a sworn translator in Estonia.
Unicount does not provide company registration service via power of attorney as we only work with online formations.