As of Read&Write for Mac v7.3, users can login using their Google, Microsoft or OKTA accounts.
As a system admin, if you would like to restrict your users to be able to only use one of these providers, you will need to run the following command on the users’ computers:
For Google:
defaults write com.texthelp.Read-Write SoleLoginProvider -string google
For Microsoft:
defaults write com.texthelp.Read-Write SoleLoginProvider -string microsoft
For OKTA:
defaults write com.texthelp.Read-Write SoleLoginProvider -string okta