ENFOLD – EMBEDDING CODE

WordPress version
5.5.3
PHP version
7.3
Enfold WordPress Template
Attempting to embed the following code
<!– Start Square Appointments Embed Code –><script src=’https://abcdefghijklmnopqrstuvwxyz.js’></script>&lt;!– End Square Appointments EmbedCode –>

I receive the following message
Warning: Characters <,>,[,] might break ALB backend or frontend. Read more if you want to use them.

I followed these instructions