Links not working and warnings pop up

Hello!
Thanks so much for developing this – really useful tool.
I’ve followed the documentation but the following warnings still pop up:
Warning: explode() expects parameter 2 to be string, array given in /home/c48hour3/public_html/wp-content/plugins/wp-gallery-custom-links/wp-gallery-custom-links.php on line 205

Warning: array_merge(): Argument #2 is not an array in /home/c48hour3/public_html/wp-content/plugins/wp-gallery-custom-links/wp-gallery-custom-links.php on line 205

Warning: explode() expects parameter 2 to be string, array given in /home/c48hour3/public_html/wp-content/plugins/wp-gallery-custom-links/wp-gallery-custom-links.php on line 216

Warning: array_merge(): Argument #1 is not an array in /home/c48hour3/public_html/wp-content/plugins/wp-gallery-custom-links/wp-gallery-custom-links.php on line 216

Warning: array_unique() expects parameter 1 to be array, null given in /home/c48hour3/public_html/wp-content/plugins/wp-gallery-custom-links/wp-gallery-custom-links.php on line 220

Warning: Invalid argument supplied for foreach() in /home/c48hour3/public_html/wp-content/plugins/wp-gallery-custom-links/wp-gallery-custom-links.php on line 222

I also tried a few solutions mentioned in the forum but while some warnings might be resolved some would still stay. Could you advise what to do?

Many thanks!