The meaning of the phrase is better understandable in relationship with the idiom "finding the holy grail", translated to Spanish as
dar con el santo grial
This is apparently an idiomatic term in a number of European languages which applies to an object that has great significance, is much desired but is impossible (or nearly impossible) to find.
As noted already, one of the meaning of "dar" (when associated with "con") is to find somebody or something
- intr. Encontrar a alguien o algo. Dar con Isabel, con el escondrijo.
Specifically, as per your request, that phrase (found in this article is a conclusion where a woman from Spain —who herself moved to Sweden and has fully adapted after living there for 20 years— gives advice on the hard path towards overcoming the large cultural gap for someone willing to immigrate. She warns about the tough difficulties of learning the language and embracing the local modes, something not instantly achievable, and as unlikely to happen immediately as finding the holy-grail
You can see that many instances of such metaphorical use come out in internet searches; like this article when referring about a ground-breaking discovery in the biological field
(...) Para poder dar con el “Santo Grial de la fecundación”, el doctor Aguilar se asoció con un grupo dirigido por Christophe Dessimoz, de la Universidad de Lausanne, Suiza. (...)
In order to find the "Holy Grail of Fertilization," Dr. Aguilar partnered with a group led by Christophe Dessimoz, from the University of Lausanne, Switzerland.