Is it permissible to withdraw from a "Jam'iyyah" (cooperative/rotating savings and credit association) after receiving the first installment, while being unable to pay the remaining installments?

It is permissible to participate in the aforementioned fund because it is a loan that does not stipulate any additional benefit for anyone. Sheikh Ibn Baz issued a fatwa to this effect, and the Council of the Senior Scholars affirmed it.

If a person promises to pay a monthly amount and then becomes unable, there is no blame upon him for stopping the payments and recovering what he has paid.

If your husband has received his first payment and no one is demanding anything from him, then it is permissible for him to withdraw. However, if some of his friends have not received the first payment, he must pay it to them, and he may recover what he paid for the second payment from whoever received it.