Good questions!
This system is basically what I use when running Knave which is a classless OSR system, so it's more or less OSR compatible. In a traditional OSR game only Thiefs can attempt to pick locks on an adventuring turn which is 10 minutes so that is where the 10 minutes comes from. My games don't generally have classes, so in general, there is a 5% chance to pick a 4 mechanism lock on an adventuring turn (10 min). A thief can take advantage (in 5e terms) when picking a lock which means they have roughly a 10% chance of picking a lock in 10 minutes.
The d6 ticks of progress refers only to picking locks under pressure. So, like, for instance a thief could try to unlock a chest or door in the middle of combat. In those situations they would make a test to see if they can make progress and then tick 1d6 progress. This is functionally identical to the way an attack roll works in most d20 games with progress standing in for HP, the d20 roll being to to-hit roll, and the d6 roll being the damage roll.
Hope this helps!