1. This code didn’t work

If I use this code, text and checkbox will show, but all fields are on the same line

.mc4wp-form p+p label {
display: block;
}

.mc4wp-form p {
display: block;
}

2. I’ve found that all checkboxes do not work with Chorme and Opera browser. I get the same error on your demo. If I use Safari Browser, it works correctly

Best
Patrick