crash my website out of existence

So a couple of days ago my website vanished. Whenever i enable Rankmath plugin my website crashes and when you try to access it …. acergamsat.com…. it downloads a file.

To solve this, you need to go into FTP and then rename the plugin rankmath to disable it and then delete the .htaccess and insert the:

# BEGIN WordPress

RewriteEngine On
RewriteRule .* – [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

# END WordPress

this will fix it. Please do becareful with the website. DO NOT DELETE ANYTHING. i am not sure what the problem is. Your plugin is conflicting with something and causing an issue. I have also provided details of FTP below in sensitive area.

Please can you get back to me as soon as psossible and let me know. RankMath is dangerous plugin that is causing me whole heap of issues.