@esmi.
If I change the file permissions, it would temporarily work but when I need to install another plugin I have to change it again.
Is there any other solution? I have full control over my server of WHM/Cpanel, when I was on my shared hosting, I could install every plugin smoothly without issues.
Issue#2: The XML sitemap generator plugin is not functioning proper. It is not rebuilding sitemap automatically whenever I publish a post.