All perfect praise be to Allah, and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
In principle, it is conditioned that each partner pays a share in the capital of a partnership at the start of business. Rather, the four Imams have agreed that the money should be available upon the start of business so as for the partnership to be valid.
It isn`t permissible for a partner to delay the payment of his share in the capital. However, he becomes a partner from the moment he pays it. Accordingly, in the above question, partnership is established amongst those who paid the 300.000JDs, and whatever is constructed in that building from that sum is theirs alone, and it is theirs when sold as well. Yet, when the person who failed to give his share at the beginning of the project manages to pay it, he becomes a partner from the moment of payment. Therefore, whatever is sold from that building, afterwards, is the right of all partners. Allah, The Almighty, said, " O ye who believe! Eat not up your property among yourselves in vanities"{An-Nisa`, 29}. And Allah knows best.