As they are just starting I don't think installment payment is necessary since the team already knows what and what will be needed to make every investor to have a complete documentation of their land without any issues.
One other reason why they shouldn't be accepting instalment payments is the issue of location of the lands, you don't expect LandDAO to issue certificate of ownership of lands to a customer who is in a different place who haven't made a complete payment to them because if they accept such kind of payments a lot of people will make instalment payments for lands instead of completing the money they will rather wait for the land to appreciate so they sell it and make more money from the sells.
There are some people that will make an agreement to have a 2 times payment package but when it is time for them to balance up they find it difficult to pay, LandDAO should discourage instalment payments to avoid a lot of financial issues.