./mongod: error while loading shared libraries: libssl.so.1.0.0: cannot open shared object file: No such file or directory
Welcome to the community @aristides_villarreal!
Can you confirm the version of Ubuntu you are running and how you installed MongoDB?
There isn’t a Ubuntu 20.20 release (this doesn’t fit their version convention), but Ubuntu 20.04 was just released this week.
As per the link @chris shared, Ubuntu 20.04 isn’t an officially supported platform yet. You can watch SERVER-44070: Add Community & Enterprise Ubuntu 20.04 x64 for updates.
MongoDB 4.2 packages are available for Ubuntu 18.04 and 16.04. For a full list of supported O/S versions for current releases of MongoDB server, see Supported Platforms.
Ubuntu 20.04, use the zip file with the 4.2.6