The digital certificates valid for submitting an offer to a tender through the Telematic Presentation of Offers or Digital Sobre functionalities, of the Public Procurement Services Platform, are those issued by an entity classified by Validador of the AOC with a security level higher than Level 3 (eg: idCAT certificate).
In the case of the electronic DNI, it must be taken into account that the signatures of the DNIe issued from April 2015 are temporarily disabled by the Spanish Ministry of the Interior.
Likewise, for this same type of certificate (electronic ID), you must bear in mind that it can contain two certificates (one for signature and one for authentication). Adobe Acobat displays both at the time of signature, however, it will only be valid for the signature of the offer summary, the signature certificate given that the authentication certificate does not have the necessary security level.
The person who signs must have powers as a representative of the company, although he can use any type of certificate. In the case of UTE, this condition applies to the legal representatives of all companies.