Error: apt-key is deprecated

Good morning every one

I tried to install opennebula version 6.0 (on ubuntu 20.04 LTS) after going through the following steps:

apt update

apt-get -y install gnupg wget apt-transport-https

wget -q -O- https://downloads.opennebula.org/repo/repo2.key | sudo apt-key add -

but it gives me this error:

Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).

how can i solve? Thanks everyone for the help