I'm a Slovak citizen living in Austria (since 14 yrs).
I've recently married a Moroccan citizen.
How can he apply to join me under EU laws of EU spouse visa?
I have no personal experience with that but your husband must in any case obtain an “Aufenthaltskarte für Angehörige aus Drittstaaten” (see also the website of the Austrian embassy in Rabat). It's distinct from the regular “Familienzusammenführung” (“regroupement familial” on the embassy's website). I can't find the right form online but it's important to insist on that as it should be easier to obtain.
Note that it's not uncommon for consulates to make difficulties or be unaware of the details of the rules. If the consulate is uncooperative, you might want to hire a lawyer or seek help from SOLVIT.