What is the ruling on benefiting from free commercial insurance provided by the employer, given that the employees filled out and signed the forms?

As long as the aforementioned insurance is a prohibited commercial insurance, it is not permissible to subscribe to it except under compulsion. However, since the company is the insurer, you may benefit from the health insurance to the extent of what the company has paid, without increase, and it is permissible to benefit even if you were not compelled.