Trip sharing works with both subscriptions but in different ways:

Free Excursion subscription: 

When you have a free Excursion subscription, you can see all the information that is contained in that trip.  

However, if the trip that was shared with you exceeds the limits by a too high number of steps, for example, then it will not be possible to modify this trip. You will only be able to view the information it contains.

Paid Escape subscription:

With an Escape subscription, there is no limit to the number of trips in a single account. 

You can have as many shared trips as you want and you can edit these trips and put them in your hand.