I am guessing from your post that you are using (or intend to use) Google Voice on your OBiTALK device. These devices have four independent Service Provider configurations, SP1--SP4. Google Voice does not support E911 service, but that has nothing to do with Google Voice itself working properly on your device -- Google Voice will work, and it has no idea whether or not you have separately subscribed to E911 service from another service provider.
So: for example, you'd configure Google Voice on SP1, and then configure a different company's service on SP2. I wouldn't waste my time on GV911. Their website has no contact information, and it looks like something some guy set up himself, with no confidence it will work in the future.
Since you can't seem to figure out how to use Anveo, then use Callcentric for E911. To do that, you sign up for one of Callcentric's free NY State inbound phone numbers, then sign up for their E911 service, and provision Callcentric on SP2. When you do this via the OBiTALK web portal, you simply click on SP2, then scroll down to the bottom of the next page and click on "OBiTALK Compatible Service Providers". On the next page, click on Callcentric and follow the instructions. There will be a box to check to use SP2 as your E911 service. The OBiTALK portal will automatically set up call routing to use SP2 for 911 calls. Callcentric charges $1.50 a month for E911 service, or you can buy their "North America Basic" outgoing call plan for $1.95 per month, which includes 120 minutes of outbound calling, and E911 for 45 cents per month more than just E911 service.
https://www.callcentric.com/rate/plans/north_america_basic/