I am using Oracle Linux 7 for my VM. I ran the virtual box guest additions 6 and it said it was starting. When I try to add shared folder from my host machine, it says that guest additions do not appear to be available on this virtual machine. What could be the problem? Please help

OK, you are running Oracle Linux for your guest machine, but what are you running on your HOST machine?
Have you installed VirtualBox Additions in the guest machine?

Your post contains almost no useful detail. We would benefit by knowing WHAT you attempted, HOW you attempted it, and the detail about your results.

Creating the share on the host should not be restricted, mounting the share ON THE GUEST is what requires the additions. That step cannot be done form the host in Linux guests. The man pages may help, the VB documentation explains more, but there are web pages of relevant content as well.

Examples: https://www.smarthomebeginner.com/mo...-ubuntu-linux/
and https://averagelinuxuser.com/virtualbox-shared-folder/