Is the hadeeth of 72 sects correct?

I have heard that the Sanad of the hadeeth is not Saheeh, not denying the meaning of it?

The hadeeth is authentic and there are many different narrations of it. The group, which is going to Paradise or firqa najia is not hair line, like if your toe is off and you’re out. It accepts differences, it does not mean everybody has to agree to everything, the sahaba differed, the tabioon differed. The fiqh or understanding may differ.