You have to purchase your insurance before you proceed to the residence permit application.
You do not have to purchase form the recommended companies below as far as policy satisfy the condition (No 2 & 3 below)
1. You would need to have your (or from someone) visa / mastercard to purchase online.
2. If you are applying for 2yrs (full time) then costs should cover up to at least 30,000 euros.
3. Maximum deductible amount is € 300.
If you are applying for 1 yr (double degree) then costs should cover up to at least 100,000 euros.
4. Read the instructions carefully before you place your order.
5. Cheapest one is Swiss Care
You will get confirmation on your email and you can submit that to the embassy.
LUT recommends: www.sipinsurance.eu
More info: http://www.migri.fi/st…/filling_in_the_application/insurance