If you see any problem in installing plugins in Publisher → Plugins, follow below steps.

1- First of all try to install one plugin from WordPress itself. For this purpose go to Plugins → Add New.

• If it is not possible to install plugin from WordPress itself, there is a restriction in “plugins” or “uploads” folder of your webhost. These folders permission should be at least 755. Change folder permission in your host panel. Ask host company support for more help.
• If it needs to enter FTP credential before adding new plugin, add FTP access to “wp-config.php” file like below. Add below codes right after database information:

// this line doesn't need change
define('FS_METHOD', 'ftpext');
// select the path to WordPress. Below is an example, select it based on your server arrangement
define('FTP_BASE', '/var/www/vhosts/example.com/httpdocs/');
// not necessary, delete it if you want
define('FTP_CONTENT_DIR', '/path/to/wordpress/wp-content/');
// not necessary, delete it if you want
define('FTP_PLUGIN_DIR ', '/path/to/wordpress/wp-content/plugins/');
// only if you use SSH
define('FTP_PUBKEY', '/home/username/.ssh/id_rsa.pub');
// only if you use SSH
define('FTP_PRIKEY', '/home/username/.ssh/id_rsa');
// FTP username
define('FTP_USER', 'username');
// FTP password
define('FTP_PASS', 'password');
// FTP host. Usually it is like this: "ftp.example.com"
define('FTP_HOST', 'host');
// use "true" if you have SSL enabled connection
define('FTP_SSL', false);

Now try again to see if the problem is solved.

Advanced cases

2- Your server might have several users for different accesses. For example, when you log into FTP, you see 755 folder permission but for “WordPress user” permission is something else. For finding about this case, search for users permission in host panel. Remember this is not the case for all servers. Even some of them have it but the option is not visible, specially in “DirectAdmin” panels.

3- Your server whitelisted WordPress.org for plugin installation. So you can download plugins from WordPress itself but cannot do it with other servers (i.e BetterStudio server). This might be solved if you contact host server support.

4- Your sever blacklisted BetterStudio IP or vice versa, BetterStudio blacklisted your website IP. In this case, you should ask host server support about this problem and give us your IP so we check it with our host company support.

Finally

It might be a problem from BetterStudio server or any other unpredictable reason. Create a support ticket and we will help you.