Yeah the link tasks seem to be the generally most confusing task to players to underatand. And of course even more so if you don’t read what Scalab says about it. Basically it’s just that you need some card you place to connect to five pips in the surrounding neighbour cards. Ie. seeing five lines go away from the card before you release it.
I will definitely do something to it on the next version. It’s too confusing and can be outright unfair and/or impossible even with higher numbers.