it's silly question , but i'm not english .
This sentence :
* The Workers have to meet the manager . (Past Tense) .
is it : The workers had to meet the manager . and use one past adverb with it .
Is that right ?
What exactly is your question?
The Workers have to meet the manager . (Past Tense) This sentence is not in the past tense.
Your second sentence is a past tense form and it doesn't necessarily need an adverb showing past time.