Index: src/wp-admin/about.php
===================================================================
--- src/wp-admin/about.php	(revision 43958)
+++ src/wp-admin/about.php	(working copy)
@@ -45,7 +45,7 @@
 				);
 				?>
 			</div>
-		<?php elseif ( ! file_exists( WP_PLUGIN_DIR . '/classic-editor/classic-editor.php' ) ) : ?>
+		<?php elseif ( ! is_plugin_active( 'classic-editor/classic-editor.php' ) ) : ?>
 			<p class="about-text">
 				<a href="#classic-editor"><?php _e( 'Learn how to keep using the old editor.' ); ?></a>
 			</p>
@@ -317,7 +317,7 @@
 
 		<hr />
 
-		<?php if ( ! file_exists( WP_PLUGIN_DIR . '/classic-editor/classic-editor.php' ) ) : ?>
+		<?php if ( ! is_plugin_active( 'classic-editor/classic-editor.php' ) ) : ?>
 			<div class="feature-section one-col" id="classic-editor">
 				<div class="col">
 					<h2><?php _e( 'Keep it Classic' ); ?></h2>
@@ -331,12 +331,24 @@
 			<div class="feature-section one-col">
 				<div class="col">
 					<p><?php _e( 'Prefer to stick with the familiar Classic Editor? No problem! Support for the Classic Editor plugin will remain in WordPress through 2021.' ); ?></p>
-					<p><?php _e( 'The Classic Editor plugin restores the previous WordPress editor and the Edit Post screen. It lets you keep using plugins that extend it, add old-style meta boxes, or otherwise depend on the previous editor. To install, visit your plugins page and click the &#8220;Install Now&#8221; button next to &#8220;Classic Editor&#8221;. After the plugin finishes installing, click &#8220;Activate&#8221;. That’s it!' ); ?></p>
+					<p>
+						<?php _e( 'The Classic Editor plugin restores the previous WordPress editor and the Edit Post screen. It lets you keep using plugins that extend it, add old-style meta boxes, or otherwise depend on the previous editor.' ); ?>
+						<?php if ( ! file_exists( WP_PLUGIN_DIR . '/classic-editor/classic-editor.php' ) ) { ?>
+							<?php _e( 'To install, visit your plugins page and click the &#8220;Install Now&#8221; button next to &#8220;Classic Editor&#8221;. After the plugin finishes installing, click &#8220;Activate&#8221;. That’s it!' ); ?>
+						<?php } else { ?>
+							<?php _e( 'The Classic Editor plugin is already installed. Visit your plugins page and click &#8220;Activate&#8221; under &#8220;Classic Editor&#8221;. That’s it!' ); ?>
+						<?php } ?>
+					</p>
 					<p><?php _e( 'Note to users of assistive technology: if you experience usability issues with the block editor, we recommend you continue to use the Classic Editor.' ); ?></p>
-					<?php if ( current_user_can( 'install_plugins' ) ) { ?>
+					<?php if ( ! file_exists( WP_PLUGIN_DIR . '/classic-editor/classic-editor.php' ) && current_user_can( 'install_plugins' ) ) { ?>
 						<div class="col cta">
 							<a class="button button-primary button-hero" href="<?php echo esc_url( wp_nonce_url( self_admin_url( 'plugin-install.php?tab=favorites&user=wordpressdotorg&save=0' ), 'save_wporg_username_' . get_current_user_id() ) ); ?>"><?php _e( 'Install the Classic Editor' ); ?></a>
 						</div>
+					<?php } elseif ( current_user_can( 'activate_plugins' ) ) { ?>
+						<?php $activate_url = wp_nonce_url( self_admin_url( 'plugins.php?action=activate&plugin=classic-editor/classic-editor.php' ), 'activate-plugin_classic-editor/classic-editor.php' ); ?>
+						<div class="col cta">
+							<a class="button button-primary button-hero" href="<?php echo esc_url( $activate_url ); ?>"><?php _e( 'Activate the Classic Editor' ); ?></a>
+						</div>
 					<?php } ?>
 				</div>
 			</div>