Premium Plugin conflicting

we have 2 plugins installed
1. Sales Countdown Timer
and
2. Sales Countdown Timer Premium for WooCommerce and WordPress

When both are active, WordPress woocommerce checkout shows an error, screenshot is attached.

when I disable the 2nd plugin (Sales Countdown Timer Premium for WooCommerce and WordPress), it works well.
means there is some problem with the second pro plugin not the first plugin.
but then what’s the use of paying for the pro version? so, request you to fix the issue kindly.