Hello,

To change the message , you need to change the code content acl app itself.It can't be done use override.
Go to root/plugins/payplans/contentacl/contentacl/app/contentacl/contentacl.php, find below mentioned line of code.

$links      = $this->getPlanlinks();

$row->text  = $row->introtext.$links;

Here you can change the string in $row->text varisble.
Update us if you have any query.