A plenary indulgence is the removal of all punishment due to sin. Even though you are forgiven in Confession, the
punishment remains unless an indulgence is granted. A plenary indulgence is granted to the faithful for making the
Stations of the Cross under the normal conditions:
• One is free from all attachment from sin
• One receives the Sacraments of Penance and the Eucharist (Within 7 days before or after completing this
devotion but if you are in the state of mortal sin, you can not complete this devotion and gain the indulgence.
You must be in the state of grace while saying the stations, even if you satisfy this requirement of Confession
after)
• One prays for the intentions of the Pope
https://acatholiclife.blogspot.com/2005/06/the-stations-of-cross.html