Login to your WordPress portal from wp-admin and navigate to the plugin module. Here you can see the Add New Button. Click on the ‘Add New’ button which will redirect you to Add Plugins Page. 
Click on ‘Upload Plugin’ Browse the WP-Plugin-Package zip and Install the Plugin. 
Click on ‘Choose File’ to activate this newly installed plugin. 
Go to the Installed plugins screen. Here, you can see SuiteCRM Customer Portal Plugin was successfully installed. But still, it’s Inactive. 
Click on ‘Activate Plugin’ to activate this newly installed plugin.