I just started playing the game and read in some strategy guides that if playing as Calis, I would get Dragon Lord Malric in the second battle in Hoaroot forest. But somehow he is not showing up for me. Is this because of the version of the game or am I doing something wrong?

you have the search the temple/monument
he is hiding there

Unless there is a specific "search" button, it's not happening for me. Just getting some gold when I enter the tile with the stones. Nothing else.

there is no 100% for finding him or any other hero, it is about 40%
1. check that you are searching the right place (if I remember correctly, it is in north-east)
2. try a bit of save/load

According to the official strategy guide, when playing Calis, you get Malric with 100% odds when you explore the Standing Stones in Hoaroot Forest. (To explore, end a unit's movement there.) There are multiple temples/shrines on that map, and IIRC the Standing Stones takes effort to go to--but the effort is well worth it!

It has to be a land unit that you use to occupy the stones.