1. Run from Ubuntu(one time)
sudo apt install virtualbox-guest-x11

2. 
sudo mount -t vboxsf Share /var/www/html

OR add to startup:
$ umask # Get umask
0022
$ id # Get uid & gid
uid=1000(USERNAME) gid=1000(USERNAME)
$ sudo nano /etc/fstab
Share /var/www/html vboxsf umask=0002,uid=1000,gid=1000 0 0
$ sudo mount -a