How can I add users to forms so someone else in my group can edit it also.

If you are looking forward to adding sub-users to your account, unfortunately, this feature has been discontinued. Please refer to How-to-Share-Forms-with-a-Sub-Account-User

You can set an email notification instead. You can send the submissions to the desired email address and allow them to edit the submissions. Below is a reference guide to achieve this.

https://www.jotform.com/help/25-Setting-up-Email-Notifications

Let me know if you have any questions or need any further help.

Ok thanks