Linux – Virtual Box VMs Ubuntu and RedHat can not access shared folders

1- I run Fedora 29 as a host.
2- I have VirtualBox 5.2.22.
3- I have Ubuntu LTS 18.4 VM and RedHatEnterpriseLinuxServer 7.
4- All my VMs have the corresponding version of Guest Access installed.
5- My shared VM folder is on a separate partition provided by the host (Fedora).
6- My shared folder on the host has 777 file permissions and is set to full access for VMs.
7- My Debian, Potash and Windows 7 VMs can easily access the shared folder.

Issue # 1: Ubuntu needs root privileges to access the shared folder.
Issue # 2: RedHat can not access the shared folder at all.

How can I fix this?