Sorry for my reply. I am only an F-Secure user (their home solutions).
how do i install free f secure
Your another topic (https://community.f-secure.com/t5/F-Secure-SAFE/f-secure-installation/m-p/115258) is not about "free"-remark. So, if your ask is not pinned to "free" -> then, another topic with already good advice about ability to check F-Secure Knowledgebase articles / how-to for your platform.
Your first topic (https://community.f-secure.com/t5/F-Secure-SAFE/is-my-free-f-secure-active/m-p/115020) is also about well advice. And if your ask is about F-Secure SAFE trial (thirty days) as free opportunity to test solution - then, usually, need to login into your My F-Secure account (https://my.f-secure.com) and to perform steps (which are possible to find with F-Secure Knowledgebase installing articles).
But if your concern is about something as promo or special offer as "free" subscription (your ISP or something else). Then, good to read related instructions for this offer / promo (created by F-Secure partners). Or to add more information and to explain what do you mean by "free F-Secure".
If your experience is about something like "voucher" or "activation key" - then it should be possible to use you My F-Secure Account (and to add such a voucher rather then to perform 'purchase/renew' after free trial end).