Warning
This import can take some time to run, additionally while running other services which are also part of the SAPB1 group will not be able to run, this should not stop order exports.
If using the Ziptastic paid version, we recommended setting Ziptastic to the free version while the import is running so that it does not use up all API calls.
To set to free version, go to Admin > System Configuration > Ziptastic API, in system config 1 set to https://zip.getziptastic.com/v2/ and clear System config 2.
Please make a note of the previous URL and license key to replace once import is completed.
ImportUserV3
To Begin Importing all users, go to admin > Data Transfer > Service Configuration,
then find the Service named 'ImportUsersV3', to immediately being pulling the data, set both “Last-Run-Time” and “DateTime Stamp” to 1985/01/01 01:00:00 
If you want it to run at the next intended time, for instance if the service is set to run once a day, set Last-Run-Time to 1985/01/01 01:00:00.
ImportUsersV4
We have begun rolling out to newer versions a Import usersV4, this differs is speed as well as how it pulls.
V4 will pull 10,000 users at a time, like we do we with price pulls.
To Begin Importing all users, go to admin > Data Transfer > Service Configuration,
then find the Service named 'ImportUsersV4', to immediately being pulling the data, set the flag to interval, the interval minutes to 1, then fetch records by 'Last Unique ID' and then last unique id to 1. 
If you want it to run at the next intended time, for instance if the service is set to run once a day, set Last-Run-Time to 1985/01/01 01:00:00.
If you also want to Import all user addresses after users has run, you will need to set the “Last-Run-Time” to 1985/01/01 01:00:00.