I also leave the steps I found to solve this error in case another user has the same problem.
the main thing about this error is that it does not connect to the server due to lack of gpg key.
with this command we make the request for the gpg key to connect to the repository without error
in my case the error gave that key 93D6889F9F0E78D5, it can change with other opi5+
the following command adds the response given by the repository and in this way we add the key to our registry to be able to connect to the repository
run the command again from the console to check if it is correct or if there is an error.
and after waiting about 5 minutes for everything to be checked and connected to the repository:
Manuel Carvajal's post in Opi5+ error omv7 install docker compose pgpkey was marked as the answer