TL;DR We’ll get there soon enough
There are plenty of costs in a web site. But the basic hosting (web server and database server) will not actually cost us very much initially. The big cost is usually labor and right now we are entirely volunteers. As we get closer to a finished product, we will need to do some fundraising (e.g., GoFundMe or a donate button on the Codidact development site or something). For legal reasons, we need to get some structure (varies by country and there are a bunch of options, but essentially a sanctioned non-profit group of some sort) before we can take any money (otherwise it is taxable to the recipient and not of any tax benefit to the giver) and the legal process itself takes some money. Since the development is itself taking a while (hopefully it will speed up soon, but the reality is that planning a big system takes time) and we will get to the legal → fundraising part soon enough.