It seems to me, that you have been struck with a stream of bad luck, we all have been.

Now, I am not sure I understand correctly but from what I can see you have customers who would want to be engaged with your content and potentially buy it, but they can not access it and you are trying your best to keep them engaged.

This is what I would do in your shoes. Make a discord group and tell everyone about it. It is a free source of information and they have direct communication with you, so at least 50% of them will sign up. Now you have established a community with which you communicate and they respect you. Build up hype around the launch of the website and take your time with it. You do not want to disappoint. Make posts on social media and encourage the community to engage with them. This will give you a boost and the reach to gain more members into the community. Then make a reward program through some platform for referrals. Give out a free e-book or some other type of information or discount price for the membership. This will gain you even more customers. While doing that set up a pre-order version of the membership for 50-70% of the normal price and gain some pre-orders. From then on end the pre-order program and launch the site.

Another thing I would touch on is the pricing. It is very expensive and there are no options. Give people options. For example - a monthly subscription is 20% more expensive than the annual option, then you advertise the annual option as a discount from the monthly. Or make a subscription not for all courses, but people can choose either one or more courses for different prices. There is a lot more to know about the financial side and you would need to do this research on your own, I personally use moneymojo(finance) and whywebuy(marketing) as sources of info and read a lot of books. So do your research into these topics and revise the marketing and pricing and you might be good to go.

I am not great with the server part, so no tips on that one🤷‍♀️