Eurail

That's pretty straightforward: add the journey to your pass, activate it and you're ready to go. If leaving from one of the bigger stations, you'll have to speak with staff at the ticket barriers so they let you through.

How do I add it to the trip planner. It tells me I can’t make the reservation on Eurail. I haven’t been able to get the pass to allow any tickets to added in Scotland or UK. I can do Ireland and then London on. 

Can you not find the jouneys in the app to add to your Pass or is your problem getting reservations?

Almost none of the trains in the UK require a mandatory reservation so the Pass alone is enough to travel.( After you have added the train to your trip and activated the journey)

I have heard some reservations for the UK can be done for free .(not through the eurail reservation service).

Hi Marvin, I can find the journey but then it tells me I can not make the reservation with Eurail and need to use ACP. I am unable to put the journey into the app and save it to make it active. If the trains in the UK don’t require a reservation, then how do I show them the pass? 

ACP should be avoided. They charge money for free reservations. The best overview of how to book reservations is on this page:

https://www.seat61.com/interrail-and-eurail-reservations.htm

Have you followed these steps?

https://www.interrail.eu/en/interrail-passes/interrail-mobile-pass/getting-started

If that doesn't work for you, then please say at which exact step you are stuck. It would be helpful if you could post a screenshot.

That is not in the railplanner App. That is just from the eurail reservation system.

Do you have a mobile Pass or a paper Pass?

I have a mobile pass. I started this here. When I went to the app, it told me that I couldn’t use it because my pass was used in the reservation system. I have an email to Eurail. So when I do it on the app, it is easier?

You dont have to reserve seats on that train. (If you want to you can do it for free at a station there or as described in the previously posted link https://www.seat61.com/interrail-and-eurail-reservations.htm )

You only have to add the journey to your trip and activate it (only activate your Pass when you actually start your trip, same for the individual days i would not activated them in advance only on the actual day of travel) 

​@Kris Kelly  have you taken a look at the links that rdvborgt posted?

Could you please post a screenshot of what you saw here? It doesn't make sense to me.