failed to open stream: Permission denied

Hi there Marco.
Im working on a test project which is hosted on free host provider.
when I try to use the plugin, after initial setup, when I press ‘Save Settings’, a message appears on the top of the page:

Warning: file_get_contents(https://api.telegram.org/***/setWebhook?url=https://botpress.org/endpoint-td.php?key=***): failed to open stream: Permission denied in /home/www/***/wp-content/plugins/telegram-bot/panel/settings.php on line 31

Can you help me with this?