ICS import error

I am trying your calendar out on a local development site. I have an ics file which imports perfectly into Outlook. I have just tried to import it into your plugin and I get an error, details below. Any suggestions?

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When seeking help with this issue, you may be asked for some of the following information:
WordPress version 5.4.2
Current theme: Poseidon Child (version 1.8.1)
Current plugin: Modern Events Calendar Lite (version 5.8.0)
PHP version 7.3.1

Error Details
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An error of type E_ERROR was caused in line 6101 of the file /Users/colin/Sites/awgb.dev.cc/wordpress/wp-content/plugins/modern-events-calendar-lite/app/libraries/main.php. Error message: Uncaught Error: Class ‘ICal\ICal’ not found in /Users/colin/Sites/awgb.dev.cc/wordpress/wp-content/plugins/modern-events-calendar-lite/app/libraries/main.php:6101
Stack trace:
#0 /Users/colin/Sites/awgb.dev.cc/wordpress/wp-content/plugins/modern-events-calendar-lite/app/features/ix.php(576): MEC_main-<parse_ics(‘/Users/colin/Si…’)
#1 /Users/colin/Sites/awgb.dev.cc/wordpress/wp-includes/class-wp-hook.php(287): MEC_feature_ix-<import_do(‘/Users/colin/Si…’)
#2 /Users/colin/Sites/awgb.dev.cc/wordpress/wp-includes/class-wp-hook.php(311): WP_Hook-<apply_filters(”, Array)
#3 /Users/colin/Sites/awgb.dev.cc/wordpress/wp-includes/plugin.php(478): WP_Hook-<do_action(Array)
#4 /Users/colin/Sites/awgb.dev.cc/wordpress/wp-content/plugins/modern-events-calendar-lite/app/features/ix.php(220): do_action(‘mec_import_file’, ‘/Users/colin/Si…’)
#5 /Users/colin/Sites/awgb.dev.cc/wordpress/wp-content/plugins/modern-events-calendar-lite/app/features/ix.php(191): MEC_feature_ix-<import_start()
#6 /Users/colin/Sites/awgb.dev.c