enough good English skills to .... ['enough' = quantity / number of skills.] They must have the number of skills they will need to keep conversations going.
good enough English skills to ... [enough = quality.] Their English must be as good as is required to keep conversations going. It gives a minimum requirement. Their English doesn't have to be perfect, but they have to be able to do what is needed.
In this context, I think you mean the second, what you have in your sample sentence.
Note: For the noun form, we hyphenate 'must-haves'.