[Hummingbird Pro] Unable to activate Hummingbird

Hi there,
I am persistently unable to activate Hummingbird Pro.
This is the message I receive:
Warning: require_once(/home/tomnabo/public_html/contemporaryschoolofpiano.com/wp-content/plugins/wp-hummingbird/core/class-installer.php):
failed to open stream: No such file or directory in /home/tomnabo/public_html/contemporaryschoolofpiano.com/wp-content/plugins/wp-hummingbird/wp-hummingbird.php on line 305

Fatal error: require_once(): Failed opening required ‘/home/tomnabo/public_html/contemporaryschoolofpiano.com/wp-content/plugins/wp-hummingbird/core/class-installer.php’
(include_path=’.:disappointed:opt/alt/php72/usr/share/pear’:wink: in /home/tomnabo/public_html/contemporaryschoolofpiano.com/wp-content/plugins/wp-hummingbird/wp-hummingbird.php on line 305

Can you help me sort this out please.

Thank you,
Monique