[The question seems to come up periodically, so I created a Consolidated Proficiency Progression table on my web site. The explanatory text is repeated below, but I cannot repeat a readable version of the table on the forum.]
"People new to the Adventurer Conqueror King System often ask what the proficiency progressions of the Player’s Companion classes are, because the core rules provide a Proficiencies Gained per Level table for the core rules classes, but the Player’s Companion does not. In fact, no table is needed.
All classed characters begin with one Class proficiency at 1st level. Then, all classed characters gain Class proficiencies based on their class’s Saving Throw progression advancement: as a Fighter (3rd, 6th, 9th, 12th), as a Cleric/Thief (4th, 8th, 12th), or as a Mage (6th, 12th). All classes have one of these underlying Saving Throw progressions.
Additionally, all characters begin with the Adventuring proficiency and one General proficiency at 1st level, plus up to one General proficiency per Intelligence bonus point (+1, +2 or +3). Then, all classed characters gain General proficiencies at 5th, 9th and 13th level.
Characters with classes having a maximum level do not gain proficiencies beyond that maximum level."