I have v14 and had the same problem. Under the sections...
Practice Information: select non person.
Provider Info:
1) on the first line of the street, type the group name; on the next line put the address;
entity type=non person.
2) Default Pins tab: type group TIN. If you use a clearinghouse, under the Extras tab, select group practice, non person.
I hope this works in v15. If you have further trouble, feel free to email me directly mcmbilling@comcast.net
Good luck!
Cheryl