What do we understand by the phrase in the scriptures 先以欲钩牵,后令入佛智?

Master Ri-Chang talks about this in his Lamrim Commentary Track 88b:

说:这样做,不好;那样做,好!先把这个利害摆在这个上头,然后呢,策发我们的心意,有了这个心意,然后呢,真正地进入。
实际上呢,正规说起来,这个是一切诸佛的真正的善巧方便。所以佛经上面说,“先以欲钩牵,后令入佛智。”喏,在这个地方,看见没有?千真万确的。所以我们要懂得喔,这个“先以欲钩牵,后令入佛智”的是这样,处处地方善巧。当你了解了这个,然后呢,你有追求的心;有追求的心,下一步才要找哪一个是正确的路子,这样步步上去的 (p278) 话,就没有问题。否则的话,你虽然见到了,你觉得:“啊,这个好!”但是因为内心当中,这种强有力的推动的力量没有,所以啊,说“好、好、好!”你也去跑,跑了两步觉得:“唉呀!这个,啊,很辛苦啊!”但是前者他有强烈的推动的力量,再辛苦,“啊!它有大利益!”有大利益的话呢,当然嘛,当然你要付出相当的努力啊!他就成功了,他就成功。反之的话,唉呀!虽然一点点小小的,你就在那儿挡不住啊,那么你就完啦!

Master Sheng Yen also has a discourse on this (unfortunately, there is no English translation):

So why this phrase 先以欲钩牵,后令入佛智 important to me?
It is to make me aware that I need motivation to study and practise Buddhism. And this is done by understanding the benefits so that I am willing to put in the effort in walking this path.

Akin to a sales person telling you all the good stuff about his product and how you will be missing out if you don’t get it.

A good example for me will probably be a promotion for gym membership: showing you pictures of buff and beautiful people and making you desire that same impact before going into the details on the effort you have to make in exercising at the gym.