Hi,
It does not depend from the presence of User Role Editor Pro. WordPress itself decide where to show UI to change default role for a new user.
For WordPress multisite:
Go to “Network ADmin -> My Sites” –> “Network Admin” –> “Sites” –> “All Sites” and select “Edit” on the site that you want to set the default role for, then click “Settings”. Scroll down and you should see “Default Role”. Set the role to ‘subscriber’(whatever you want) and save.
