Blog templates still now working

Hello
I have already reported this as a problem with another website.
I have a multisite installation on http://pontypridd.ourlocal.town/
It all works fine until I install New Blog Templates. If I then sign up as a new user (http://pontypridd.ourlocal.town/wp-signup.php) and create a new website, I cannot access the admin area as that new user.
Logged in as super admin all is fine, but as my newly created user, it does not work.

Please help.
Thanks
Duncan