More error on plugin

hello, i have several errors with the plugin. i have installed contact form 7 and the sending is done via postman. if i send a test email it works fine, but in the form it doesn’t work, also i have many errors in the server logs:

Got error ‘PHP message: PHP Warning: Trying to access array offset on false in /var/www/vhosts/xxxxxxx/httpdocs/wp-content/plugins/postman-smtp/Postman/PostmanOAuthToken.php on line 45; PHP message: PHP Warning: Trying to access array offset on false in /var/www/vhosts/xxxxxxx/httpdocs/wp-content/plugins/postman-smtp/Postman/PostmanOAuthToken.php on line 46; PHP message: PHP Warning: Trying to access array offset on false in /var/www/vhosts/xxxxxxx/httpdocs/wp-content/plugins/postman-smtp/Postman/PostmanOAuthToken.php on line 47; PHP message: PHP Warning: Trying to access array offset on false in /var/www/vhosts/xxxxxxx/httpdocs/wp-content/plugins/postman-smtp/Postman/PostmanOAuthToken.php on line 48’, referer: https://xxxxxxx/

Also if I try to deactivate the plugin there is another error and it is not possible to do so, it is not possible to deactivate the plugin. This is the error:

Un errore di E_ERROR è stato causato nella linea 212 del file /var/www/vhosts/xxxxxxx/httpdocs/wp-content/plugins/postman-smtp/Postman/Postman-Mail/PostmanMyMailConnector.php. Messaggio di errore: Uncaught Error: Undefined constant “d” in /var/www/vhosts/xxxxxxx/httpdocs/wp-content/plugins/postman-smtp/Postman/Postman-Mail/PostmanMyMailConnector.php:212
Stack trace: 0 /var/www/vhosts/xxxxxxx/httpdocs/wp-includes/class-wp-hook.php(324): PostmanMyMailConnector->deactivate() 1 /var/www/vhosts/xxxxxxx/httpdocs/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters() 2 /var/www/vhosts/xxxxxxx/httpdocs/wp-includes/plugin.php(517): WP_Hook->do_action() 3 /var/www/vhosts/xxxxxxx/httpdocs/wp-admin/includes/plugin.php(826): do_action() 4 /var/www/vhosts/xxxxxxx/httpdocs/wp-admin/plugins.php(211): deactivate_plugins() 5 {main}

thrown