How to create USER or Group field using SAIL Component ?...

Currently there is no explicit user or group field in SAIL. The documentation lists the available components:
forum.appian.com/.../SAIL_Components

I am testing the SAIL Components at this moment. There is no component for user or group.

But you can use dropdown or picker to fulfil your business requirement. In my use case, user will select working team (group) from a dropdown first and then a picker will be enabled with all users in the group.

The only concern is performance if the group has a large number of users.

You can also use the touser() function

Please also note that picker is not supported in mobile phone interface.