which version of turbotax do I need to buy when I have an installment plan?

[xmasbaby0]

An installment plan for what, exactly?   If you mean you are on a payment plan with the IRS to pay tax you owe, you do not pick your software program using that as a factor.   If you owe the IRS, and you are getting a refund for 2024, no matter what version of the software  you use, the IRS will automatically use your 2024 refund toward the tax you owe.   You do not enter anything about it on your tax return.

Choose the software version that suits the kind of income you will need to enter.

Or did you mean something else by "installment plan?"