Errors after installing and activating the plugin

Thank you for the response!

Here’s the Diagnostic Test Report:

Mailer: postsmtp
HostName: [removing this for security reasons]
cURL Version: 7.85.0
OpenSSL Version: OpenSSL/3.0.9
OS: Linux c108297.sgvps.net 5.15.126-MCIclouder399 #399 SMP PREEMPT Wed Aug 16 16:53:17 EEST 2023 x86_64
PHP: Linux 7.4.33 C
PHP Dependencies: iconv=Yes, spl_autoload=Yes, openssl=Yes, sockets=Yes, allow_url_fopen=Yes, mcrypt=No, zlib_encode=Yes
WordPress: 6.4.1 en_US UTF-8
WordPress Theme: Divi Child
WordPress Plugins: ManageWP - Worker, Post SMTP, Gravity Forms, Conditional Menus, Divi Overlays, Duplicate Page, Yoast Duplicate Post, Gravity Divi - Gravity Forms Styler for Divi, Gravity Forms Help Scout Add-On, WP Armour - Honeypot Anti Spam, Image Intense, Redirection, Search Engine Visibility, Speed Optimizer, Security Optimizer, Wordfence Security, Yoast SEO, WP101 Video Tutorial Plugin
WordPress wp_mail Owner: /home/customer/www/[domain]/public_html/wp-content/plugins/post-smtp/Postman/PostmanWpMailBinder.php
WordPress wp_mail Filter(s): PostsmtpMailer->get_mail_args
WordPress wp_mail_from Filter(s): wordfence::fixWPMailFromAddress
Postman: 2.8.5
Postman Sender Domain (Envelope|Message): gmail.com | gmail.com
Postman Prevent Message Sender Override (Email|Name): No | No
Postman Active Transport: Default (smtp:none:none://localhost:25)
Postman Active Transport Status (Ready|Connected): No | Yes
Postman Selected Transport: Gmail API (https:login://www.googleapis.com:443)
Postman Selected Transport Status (Ready|Connected): No | Yes
Postman Deliveries (Success|Fail): 0 | 0
Postman File Locking (Enabled|Temp Dir): No | /tmp

Hello,

We were previously using WP Mail SMTP by WPForms, then deactivated and uninstalled it. And then I installed Post SMTP. Upon activation, I saw the errors. I initially ignored them but when I proceeded with using the setup wizard, I wasn’t able to save my changes because it would redirect me to a page containing nothing but the errors.