OP you say you came here to explore donor sperm through a clinic despite being quite set on the idea of using Fred's sperm.
You say you have done a lot of research and this has been years in the making, but you don't know even know your nearest clinic and I don't understand why you would even explore this if you have already got written agreements drafted (though these have not been drafted through a lawyer so I don't think you have really researched this as you say).
You are clear that you are not in love with this man, want nothing from him but his sperm, his partner supports this and even suggested it, he has done this before and has several other children this way as well as his own, and everything sounds agreed and set up so why are you asking about donor sperm through the official route? He isn't even suggesting sex so you aren't under pressure and he live close by enough to deliver fresh sperm (though I would advise against is in this lock down and during a pandemic anyway as the virus is present in semen).
A one night stand usually involves contraception and protection against STDs and STIs and is not for the purposes of making a baby! If it does result in pregnancy it can also result in abortion. A woman who wants to get pregnant through a one night stand isn't being honest about her motives and is risking her health and the health of a baby. I would advise anyone strongly against it because it is not safe for several reasons.
(You really should listen to that podcast so to think more about the child you want to create, the woman speaking was in a similar position to you and she has learnt so much from the process, it was very thought provoking.)
It's clear you have no intention of pursuing the proper, regulated method that is available and managed for the benefit of women like you and for any children you might have through official donor sperm, with counselling, advice and support. You are rejecting all that to go your own way. No one can stop you, just don't pay him as that is illegal.
And if it's not about the cost (as Fred comes for free) and you have no concerns about his health (though you have some over your own) I'm not sure what the point of your enquiry was.
Others have suggested, as I have, that you have legal advice and you go the formal route, through a clinic, so I am not the only poster expressing concern for your plans.
I also wonder if you've know this man for 9 years what on Earth has taken you so long? His sperm is only getting older and slower whilst you wait.
As a PP said, as this thread has continued something doesn't ring true, it doesn't add up. I hope if you are successful and get pregnant that the child you have with Fred grows happy and strong and that he will want to know his son or daughter, even just a little bit, and be in the child's life in a positive way and the child will know his or her siblings.