Probably a check. If this was a while ago or a smaller landlord that just doesn’t have a fancypants website with a payment portal they probably have to drop a check off at their office each month. I had to do that in the year of our lord two thousand and twenty one before I got my house
Edit to add: the lowish rent definitely supports either reason too. Small towns most businesses have no web presence beyond a Facebook page or maybe some static html made by the local computer place 5-15 years ago that they haven’t updated since then because they aren’t seeing the value in spending money to update it. It really is like going back in time technologically a good 15 years living in a small town
For almost the first year I lived there I paid rent in person by cheque to a management company office. It was a midtown manhatten apartment in a nice ish building less than a decade ago. They also forgot to cash the bankers draft I had written up for my deposit (five fucking figures that they just didn’t notice for years). Real Estate has a surprising number of absolute clowns still for some reason. I guess because it’s been easy money for asset owners so they chaff wasn’t being squeezed out.