I've just installed Malwarebytes on the bursar's own laptop which is XP Pro SP3. When I update I get an error message which googling reveals from MWB's forum
Well the machine setup you describe is for a business machine not a consumer. The free product is not allowed to be used on any business type machine.
If you wish for support on a business machine then you need to purchase a license for the product.
However, if I run it on my school computer with the same OS, it updates ok and when I check the log, both computers have the same database version dated yesterday but hers has more fingerprints.