After plugin activation some warnings appeared in WP Backend

Warning: constant(): Couldn’t find constant CMS2CMS_ACCESS_KEY in /home/p313026/www/oil.skvok.ru/wp-content/plugins/cms2cms-html-to-wp-convertor/ui.php on line 29

Warning: Invalid argument supplied for foreach() in /home/p313026/www/oil.skvok.ru/wp-content/plugins/cms2cms-html-to-wp-convertor/cms2cms/loader.php on line 35

What the reason and how to fix it?

Warning: file_get_contents(https://localhost/wordpres/wp-content/plugins/cms2cms-html-to-wp-convertor//config.txt) [function.file-get-contents]: failed to open stream: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. in C:\xampp\htdocs\wordpres\wp-content\plugins\cms2cms-html-to-wp-convertor\ui.php on line 25

Fatal error: Maximum execution time of 60 seconds exceeded in C:\xampp\htdocs\wordpres\wp-content\plugins\cms2cms-html-to-wp-convertor\ui.php on line 25

https://www.ads-software.com/plugins/cms2cms-html-to-wp-convertor/

I tried this out and it did not work. I found another far better way to do what I needed and ask cms2cms to remove my details. They basically said I gave permission to get emails when I signed up to use this service.
I was eventually told my email was unsubscribed. Just today I have now go 4 more emails from them pushing their useless service…

CMS2CMS – Sort your system out and put an unsubscribe link on your emails like is legally required..

https://www.ads-software.com/plugins/cms2cms-html-to-wp-convertor/

Would that be converted?

https://www.ads-software.com/plugins/cms2cms-html-to-wp-convertor/

Why are you stating that you do HTML to WordPress Convertor, which in reality is joomla to wordpress. This is false advertisement. Remove it asap

https://www.ads-software.com/plugins/cms2cms-html-to-wp-convertor/screenshots/

https://www.ads-software.com/plugins/cms2cms-html-to-wp-convertor/