Is it permissible to train for free in the field of marketing at a company that sells alcohol and soft drinks, knowing that this training may help in obtaining a job after four years of unemployment?

It is permissible to train for and work in serving permissible soft drinks, while avoiding serving alcoholic beverages. However, if one is compelled to serve alcohol or assist in its serving, then it is not permissible. And whoever fears Allah, He will make his matter easy and provide for him from where he does not expect.