That step is executes after a yum install. If your yum install didn’t succeed then adding this would indeed block installing.
You can specify any available version of MongoDB. However
yumupgrades the packages when a newer version becomes available. To prevent unintended upgrades, pin the package. To pin a package, add the followingexcludedirective to your/etc/yum.conffile:
exclude=mongodb-org,mongodb-org-server,mongodb-org-shell,mongodb-org-mongos,mongodb-org-tools
Thanks for following up, it was a head scratcher.