Clean reinstall, load theme

having a relatively minor problem with WooCommerce on my Hiker theme template site which couldn’t be resolved. Since there was years of junk on the server, I decided to do a clean reinstall.
Wipe WP files
Kill DBs
Create new DB
Install WP
Upload the newest version of Hiker
First time after going through this, I immediately clicked Activate and got this error

Fatal error: Uncaught Error: Call to undefined function mysql_num_rows() in /home3/ma7chb0y/public_html/timscottphotography.com/wp-content/themes/hiker/option-tree/includes/ot-functions-admin.php:670 Stack trace: #0 /home3/ma7chb0y/public_html/timscottphotography.com/wp-includes/class-wp-hook.php(298): ot_default_settings(”) #1 /home3/ma7chb0y/public_html/timscottphotography.com/wp-includes/class-wp-hook.php(323): WP_Hook->apply_filters(NULL, Array) #2 /home3/ma7chb0y/public_html/timscottphotography.com/wp-includes/plugin.php(453): WP_Hook->do_action(Array) #3 /home3/ma7chb0y/public_html/timscottphotography.com/wp-admin/admin.php(154): do_action(‘admin_init’) #4 /home3/ma7chb0y/public_html/timscottphotography.com/wp-admin/customize.php(13): require_once(‘/home3/ma7chb0y…’) #5 {main} thrown in /home3/ma7chb0y/public_html/timscottphotography.com/wp-content/themes/hiker/option-tree/includes/ot-functions-admin.php on line 670

Since activated, I could no longer go to the Admin panel so I had to repeat all those steps again.
The next time, I did Live Preview and got the same error. So, I redownloaded the theme straight from the distributor – https://themeforest.net/item/hiker-wordpress-photography-theme/7021802
and got the same error.

Any ideas how to fix this?

The blog I need help with is timscottphotography.com.