ACH and giving access to my account

[Roy Gottesdiener]

About to purchase a duplex with a private lender (they seem legit, saw their name plenty of times on BP and good reviews, but can never be too sure).

As this is the first time I purchase a property with a lender I'm a bit worried I need to give access to my account so they can debit monthly, because basically they can take as much as they want. Are there any ways to protect myself?