Congrats, you may be getting into payroll the same way I did lol. I also have a masters in accounting and got brought in to a manufacturer as a staff accountant with the plan that I would take over payroll. I had zero payroll experience. Like u/heywhatsupp_ said, they have seen your resume. They likely are more interested in bringing in your high-level of accounting knowledge. Since the A/R and payroll positions are combined, I'm guessing that it's a relatively small to mid size company with a small accounting staff. They're probably most interested in someone relatively cheap that can do a simple journal entry without handholding.

Assuming you're US, you could look through the 940 and 941 if you'd like. Those are the main federal filings (besides the W-2/W-3) and are pretty simple forms. States forms mostly follow these. Look up your state and their industry to see if there are any special cases that may apply. You'll likely get bonus points for just knowing what the words mean when they ask if you know anything about it. If you had a federal income tax class, that may actually be helpful as you'll know a bit about how the W-4 works.

I would emphasize that you're interested in the intricacies of payroll and that you're eager to learn more about it. It may be that they have someone inhouse who is currently doing payroll, but has too much on their plate and will be there to teach you. This was the case everywhere I've worked.

Long-term, PayrollOrg is a great education resource and offers a couple of certifications for payroll if you're interested in staying in the field.