potty training adult dog advice

hey friends, i'm taking in a 2 year old foster dog in a couple of weeks who is not completely potty trained. i don't have all the details yet but she has been through some trauma and several different owners (no idea why, she's a friendly lil sweetheart). i've potty trained a few puppies before but never an adult dog who probably has bad habits engrained already. i should not i'm in an apartment so no yard. she will not be left alone longer than maybe 4 hours majority of the time. any resources or advice?