Is the salary that the questioner received from a company, whose contract type he does not know and where he did not clock in, lawful or unlawful, and how can he atone for it if it was unlawful?

It is not permissible to take money from the employer without actual work, unless the exemption from work is issued by an authorized official from the company, in which case the salary becomes a gift. Otherwise, the money must be returned to the company; if that is not possible, it should be spent on public interests and charitable causes.