For the custom gallery link you will need to have your IT team update your DNS records accordingly.
This is a somewhat straightforward process but does require someone with login information and knowledge on how to update your DNS records
If you choose not to create a custom subdomain your guests will be directed to myboothpic.co/gallery_code in order to view the gallery.
If you choose yes they will be directed to subdomain.yourdomain.com/gallery_code where subdomain can be whatever you would like.
Examples:
mypics.digibooths.com
my360.digibooths.com