@jstanek Welcome to the community.
I believe you have a typo of the domain name in your post. I think you meant americanlabrescue.com - not amercian...
Assuming that, the chain you serve is the so-called 'short-chain' ending with the ISRG Root X1. Nothing inherently wrong with that but it will exclude older Android clients and certain others.
As to the problem in the title of your post, I am not an Apple expert but there are apparently problems with older OS X. The below post by a Lets Encrypt Engineer explains that. If that is not helpful, please provide more details about the version of the clients OS and browser having problems reaching your site.