Hi lorraine10,
Thanks for your post, at this time, only some companies have the option to send from Gmail, we hope to have this option for everyone soon.
The Gmail address can only be set up by Amin level users (Company Admin and Master Admins) so it may be worth checking that you have the permissions to do this to eliminate that this is causing an issue. For further information please see here, get back to us below if you have any questions. 🙇:female_sign: