Upgrading Mongdb from 3.6.8 to 4.0 when installed with Apt - Ubuntu 20.04 focal

Hello, I am needing to upgrade Mongodb (which was installed using apt) from 3.6.8 - ubuntu default - to version 4.0 or higher.

In checking the v4.0 manual (Install MongoDB Community Edition on Ubuntu — MongoDB Manual) only 18.04 bionic is supported. Also according to the manual “If you installed MongoDB from the MongoDB apt, yum, dnf, or zypper repositories, you should upgrade to 4.0 using your package manager.”(https://www.mongodb.com/docs/manual/release-notes/4.0-upgrade-replica-set/).

If version 3.6 needs to be upgraded to 4.0 (to then be upgraded beyond that as version 4.4 is supported on 20.04) and should be done using the package manager but version 4.0 isn’t supported on 20.04 can someone point me to the procedure I should follow? Thanks.

Any ideas on this? Can anyone share a link or experience on what they did?

Really interested in anyone’s experience relating to this.