Errow message during registration

using version 2.0.8 of plugin.

when i tried to register for a new user on a incognito tab on the page http://www.sgschoolconfessions.com/wp-login.php?action=register

after i hit the submit button an error message appears:

“Not Acceptable!

An appropriate representation of the requested resource could not be found on this server. This error was generated by Mod_Security.”

pls help

https://ww.wp.xz.cn/plugins/pie-register/