Hello,
1-For the permissions: i’m not sure but looks like you don’t have the right to install/activate plugins. Are you sure you’re using an admin account with alll the defaults capabilities?
2-For the errors: there is always a php.ini file, you just don’t have access to it. I suggest you contact your hosting company and ask them to help you make the changes because a lot of them don’t let the customers edit the php settings by themselves.